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How different are these terms: Phylloclade, Phyllode, Cladophyll and Cladode?

How different are these terms: Phylloclade, Phyllode, Cladophyll and Cladode?



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We started with Plant Morphology in class (specifically, the morphology of angiosperms).

My teacher's provided us with the following terms and their definitions.

  • Phylloclade

    A modified stem that is flattened or cylindrical and capable of unlimited growth. They are green and capable of photosynthesis. Examples include; Opuntia, Epiphyllum, Casuarina, Euphorbia.

  • Cladophyll (also called a Cladode)

    A modified stem capable of limited growth. They are green and capable of photosynthesis. They bear an axillary bud at the their middle, from which flowers develop. Examples include; Ruscus, and some Asparagus species.

No mention of the term "Phyllode"… yet.


Now I'm sure I understand the definitions provided, however, I'm beginning to seriously question the validity of those definitions.

Apparently, these terms aren't documented very well, and after two hours of constant Googling, I arrived at:

  • Phylloclade (From the Wikipedia page of the same name)

    Phylloclades and cladodes are flattened, photosynthetic shoots, which are usually considered to be modified branches. The two terms are used either differently or interchangeably by different authors. [Examples provided]: Ruscus, Phyllanthus and some Asparagus species.

  • Cladophyll (From the Wikipedia page for "Petiole")

    In some plants, the petioles are flattened and widened, to become phyllodes or phyllodia, or cladophylls and the true leaves may be reduced or absent. Thus, the phyllode comes to serve the functions of the leaf. [Examples provided]: Some Acacia species.


This is annoying, seriously.

According to the definitions provided by my teacher, we're dealing with something called a "Phylloclade" and something else called a "Cladophyll" (= "Cladode"). They don't mention the term "Phyllode", though.

Based on the Wikipedia definitions, however, we're dealing with something called a "Phylloclade (= "Cladode", if you ignore minor d̶i̶s̶r̶e̶p̶a̶n̶c̶i̶e̶s̶ differences in their definitions, which are mentioned later on in the Wikipedia article), and something else called a "Cladophyll" (= "Phyllode")


My questions:

1) What are the correct definitions of the terms "Phylloclade", "Phyllode", "Cladophyll" and "Cladode"?

2) Are the examples (provided in my notes and the Wikipedia articles) actually relevant/correct? For example: Does Ruscus possess Phylloclades (as suggested by the Wikipedia article) or does it possess Cladophylls (as suggested by my teacher)?

3) Building on question (1): Does "Phylloclade" = "Cladode", and "Cladophyll" = "Phyllode"?


Apart from the discrepancy of the cladophyll term I can say that both your teacher and the wiki page are correct.

If you read the Wiki page carefully it states that

Phylloclades and cladodes are flattened, photosynthetic shoots, which are usually considered to be modified branches. The two terms are used either differently or interchangeably by different authors.

(As you have also quoted)

This is simple because both phylloclades and cladodes are stem modification for photosynthesis and xerophytic adaptation as well. So in this context they are interchangeable

Also if you have further read the article it states why the terms are interchangeable and why not. The different levels of definition are given:

Definitions of the terms "phylloclade" and "cladode" vary. All agree that they are flattened structures that are photosynthetic and resemble leaf-like branches.


one definition, phylloclades are a subset of cladodes, namely those that greatly resemble or perform the function of leaves,[2] as in Butcher's broom (Ruscus aculeatus) as well as Phyllanthus and some Asparagus species.

The definition given by your teacher can be interpreted by these two definitions stated in the Wiki page:

By an alternative definition, cladodes are distinguished by their limited growth and that they involve only one or two internodes.[3] By this definition, some of the most leaf-like structures are cladodes, rather than phylloclades. By that definition, Phyllanthus has phylloclades, but Ruscus and Asparagus have cladodes.


Another definition uses "phylloclade" to refer a portion of a leaf-like stem or branch with multiple nodes and internodes, and "cladode" for a single internode of a phylloclade.

But phyllode is a leaf modification, specifically a modification of the petiole for photosynthesis and a xerophytic adaptation to some extent. (Source is the Wiki page itself)

So to conclude

  • phyllode is completely different from phylloclade and cladodes.

  • Taking the type of morphology of the plant into consideration and the definition used, phylloclade and cladodes may be used interchangeably or may not be.


Just Remember the two main ; Phylloclade is a STEM modification for desert like area in which the stem becomes broad and fattened (in opuntia) or cylindrical(in euphorbia) !!

Phyllode is a LEAF modification and found in Australian Acasia in which the PETIOLE becomes a little braod and start performing photosynthesis!!

More key differences can be found on here https://www.differencebtw.com/difference-between-phyllode-and-phylloclade/


In flowering plants, a petiole is generally slender and chiefly renders support by attaching the leaf blade to the stem. In some plants, the petioles become modified or specialized in a way that they become leaf-like in appearance (expanded) and serve not only to support the leaf but to carry out photosynthesis as well.

Not all leaves have petioles. Some are, instead, attached directly to the plant stem. Leaves that do not have petioles, such as those of the broomrape family, are called sessile leaves. Nearly-petiolate leaves are those that have very short petioles. Grasses do not generally have petioles, but some have petiole-like structures called pseudopetioles. Yet another form of the petiole is the rachis—a continuation of the petiole which attaches compound leaves to their plant stems.


In which of these options, the plants are correctly matched with the modification seen in them? Phylloclade Phyllode Cladode (i)

In which of these options, the plants are correctly matched with the modification seen in them? Phylloclade Phyllode Cladode (i) Opuntia Asparagus Acacia (ii) Casuarina Opuntia Asparagus (iii) Euphorbia Asparagus Casuarina (iv) Euphorbia Opuntia Acacia A (i) Correct Answer B (ii) Your Answer (iii) (iv)

Ansaci Lexplain 9 a means it • Phylloc lade is a flattened branch or stem joint that resembles leafs do the function of leaf en- Opuntia . Download the app for the rest

Morphology of Flowering Plants

A NOVETNLETS (a) / (Unicostate or pinnate - This type of venation is having only one principal vein or midrib that gives Multicostate or palmate - In this type of venation many principal veins arising from the tip of petiole Multicostate Unicostate Zizyphus C Ber RETICULATE VENATION 2. Parallel venation - In this type of venation, all veins run parallel to each other and they donot form network They are of 2 types 290 (a) Unicostate or pinnate : This type of pattern is having only one principal vein, that gives off many lateral veins, which proceed toward the margin of leaf blade in a parallel manner but they donot have ninlop 5) Multicostate or palmate : This type of pattern is having many principal veins ansing from the tip of the petiole and proceeding upwards, eg. Grass cereals Reticulate venation is of 2 types lateral veins which proceed towards margin and apex of lamin eg. Peapar motwork Imara 26 and proceed upward eg. Zizyphus (Ber) Paloste

Morphology of Flowering Plants

Placenta Mesocarp- + endocarp Epicarp Seeds Mesocarp + endocarp True part Placenta T.S. of Cucumber L.S. of Tomato POME. This fruit develops from bi or multicarpellary, syncarpous, inferior ovary, The rind and the fruit and seeds are present in it. Eg, Apple, Pear, These are false fruits Fleshy swollen thalamus sponge are made up of thalamus. The main part of the ovary is like to cartilage. It remains inside Fleshy thalamus Seeds L.S. of Apple of these fruits is edible part. Fleshy thalamus Placenta Mesocarp Seeds endocarp Epicarp Mesocarp + endocarp Seeds Seeds True part of fruit Placenta L.S. of Tomato L.S. of Apple T.S. of Cucumber

Morphology of Flowering Plants

EXERCISES 1. What is meant by modification of root? What type of modification of root is found in the: (a) Banyan tree (b) Turnip (c) Mangrove trees 2. Justify the following statements on the basis of external features: (i) Underground parts of a plant are not always roots. (ii) Flower is a modified shoot. minnately compound leaf different from a palmately compound leaf?


1st PUC Biology Plant Kingdom NCERT Text Book Questions and Answers

Question 1.
What is meant by modification of root?
Answer:
When roots are modified to carry out some additional functions like storage of food, additional mechanical support, other than the absorption of water, minerals and main support to plant then, they represent a modification of roots.

Question 2.
What type? of modification of root is found in the:
(a) Banyan tree
(b) Turnip
(c) Mangrove trees
Answer:
(a) In banyan tree, adventitious roots are modified into hanging supporting roots for a giant banyan tree. These roots develop from branches and provides additional support to reach down the ground. Hence this modification is prop root.
(b) Taproots of turnip get swollen and modified for storage of food. Such roots are called napiform roots.
(c) In mangrove tree, roots come out from the ground and grow vertically. Such roots are called pneumatophores or respiratory roots. They help to get oxygen for respiration, to get modified into pneumatic structures. Mangrove trees generally grow in a marshy areas.

Question 3.
Justify the following statements on the basis of external features:
1. Underground parts of a plant are not always roots.
2. Flower is a modified shoot.
Answer:
1. Underground parts of a plant are not always roots as some perennial herbs develop their stems underground for the purpose of perennation, and food storage during unfavourable conditions. The stem produces aerial branches every year when conditions become favourable. The underground stems act as storage organs and also help in vegetative propagation by means of their buds. These stems are non-green and leafless like roots but differ from them on the basis of:

  • presence of nodes and internodes, scale-leaves, and axillary and terminals buds
  • absence of root hair and root cap.

2. Flower is highly modified and condensed
shoot meant essentially for the sexual reproduction of the plant. Calyx, corolla, androecium and gynoecium are modifications of leaf for playing a various role in reproduction.

Question 4.
How is a pinnately compound leaf different from a palmately compound leaf?
Answer:
Phyllotaxy is the pattern of arrangement of leaves at the stem or branch. This is usually of three types :

  • Alternate: In this arrangement, a single leaf arises at each node in an alternate manner. e.g., in china rose, mustard & sunflower plants.
  • Opposite: A pair of leaves arise on each node in the manner that these lie opposite to each other, e.g. guava leaves.
  • Whorl: In this arrangement, more than two leaves arise at the node and form a whorl. e.g., in Alstonia, Nerium (Oleander).

Question 5.
Explain with suitable examples the different types of phyllotaxy.
Answer:
Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. This is usually of three types alternate, opposite, whorled. In the alternate type of phyllotaxy, a single leaf arises at each node in m alternate manner, as in china rose, mustard, and sunflower plants. In opposite types, a pair of leaves arise at each node and lie opposite to each other as in holotropic, Guava plants. If more than two leaves arise at a node and form a whorl, it is called whorled, as Nerium, Alstonia.

Question 6.
Define the following terms:

  1. aestivation
  2. placentation
  3. actinomorphic
  4. zygomorphic
  5. superior ovary
  6. perigynous flower
  7. epipetalous stamen
  1. Aestivation: It is the arrangement of sepals/ petals in relation to one another in floral buds. It is of four types open, valvate, twisted, and imbricate.
  2. Placentation: The manner of arrangement of placentae inside the cavity of the ovary for providing cushions is called placentation.
  3. Actinomorphic: A flower that can be vertically divided into two equal halves by any vertical division passing through a centre is actinomorphic. Such flowers are radially symmetrical, e.g., Mustard.
  4. Zygomorphic: A flower that can be vertically divided into two equal halves in one vertical plane only. Such flowers are bilaterally symmetrical, e.g., Pea, Salvia.
  5. Superior ovary: When the flower is hypogynous, it has an ovary attached to the receptacle above the attachments of floral parts, ex.- berries, drupes etc.
  6. Perigynous: When the sepals, petals, and stamens appear to be arising from the middle of the ovary, the flower is described as perigynous. In these flowers, the ovary is semi-inferior, e.g., Saxifraga.
  7. Epipetalous stamen: Stamen are attached with petals.

Question 7.
Differential between
(a) Racemose and cymose Inflorescence
(b) Fibrous root and adventitious root
(c) Apocarpous and syncarpous ovary
Answer:
(a) Racemose and cymose inflorescence:
In the racemose type of inflorescence, the main axis continues to grow, the flowers are borne laterally in acropetal succession. Acropetal succession means that older flowers are at the base and younger flowers are near the apex. In the cymose type of inflorescence the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order. In basipetal succession older flowers are at the apex and younger flowers are near the base.

(b) Fibrous root and adventitious root:
In monocotyledonous plants, the primary root is short-lived and is replaced by a large number of roots. These roots originate from the base of the stem and constitute the fibrous root system, as seen in the wheat plant. In some plants, like grass, monster, and the banyan tree, roots arise from parts of the plant other than the radicle and are called adventitious roots.

(c) Apocarpous and syncarpous ovary:
When more than one carpel is present, they may be free as in lotus and rose and are called apocarpous. When carpels are fused as in mustard and tomato, they are termed syncarpous.

Question 8.
Draw the labelled diagram of the following:
(i) gram seed
(ii) V.S. of maize seed
Answer:

Question 9.
Describe modifications of the stem with suitable examples.
Answer:
Modifications of Stem
Food Storage: Stems are modified to perform different functions. Underground stems of potato, ginger, turmeric, Colocasia are modified to store food in them. They also act as organs of perennation to tide over conditions unfavourable for growth.
Tendrils Stem: Tendrils which develop from axillary buds, are slender and spirally coiled and help plants to climb, such as in gourds (cucumber, pumpkins, watermelon) and grapevines.
Thorns: Axillary buds of stems may also get modified into woody, straight and pointed thorns.
Thoms are found in many plants such as Citrus, Bougainvillea. They protect plants from grazing animals.
Some plants of arid regions modify their stems into flattened (Opuntia), or fleshy cylindrical (Euphorbia) structures.
They contain chlorophyll and carry out photosynthesis. Vegetative
Reproduction: Underground stems of some plants such as grass and strawberry, etc., spread to new niches and when older parts die, new plants are formed.
In plants, like mint and jasmine, a slender lateral branch arises from the base of the main axis and after growing aerially for some time arch downwards to touch the ground.
A lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots are found in aquatic plants like Pistia and Eichhornia. In banana, pineapple, and Chrysanthemum, the lateral branches originate from the basal.

Question 10.
Take one flower each of the families Fabaceae and Solanaceae and write its semi-technical description. Also, draw their floral diagram after studying them.
Answer:

This family was earlier called Papilionoideae, a subfamily of family Leguminosae. It is distributed all over the world.

  • Vegetative characters: Trees, shrubs, herbs, root with root nodules Stem: erect or climber
  • Leaves: alternate, pinnately compound or simple, leaf base, pulvinate, stipulate, venation reticulate.
  • Floral characters: Inflorescence: racemose Flower: bisexual, zygomorphic Calyx: Sepals five, gamosepalous, imbricate aestivation.
  • Corolla: Petals five, polypetalous,
    papilionaceous, consisting of a posterior standard, two lateral wings, two anterior ones forming a kneel (enclosing stamens and pistil), vexillary aestivation.
  • Androecium: ten, diadelphous, anther dithecous
  • Gynoecium: Ovary superior, monocarpellary, unilocular with many ovules, style
  • single
  • Fruit: legume, seed, one to many, non- endospermic
    Floral Formula:
  • Economic Importance: Many plants belonging to the family are sources of pulses (gram, arhar, sem, moong, soyabean) edible oil (soyabean, groundnut) dye (indigofera) fibres (sunhemp) fodder (Sesbania, Trifolium), ornamentals (lupin, sweet, pea) medicine (muliathi).

It is a large family, commonly called as the ‘potato family’. It is widely distributed in tropics, subtropics and even temperate zones

Vegetative Characters:
Plants mostly herbs, shrubs, and small trees

  • Stem: herbaceous rarely woody, aerial erect, cylindrical, branched, solid of hollow, hairy or glabrous, underground stem in potato (Solanum tuberosum)
  • Leaves: alternate, simple, rarely pinnately compound, exstipulate venation reticulate
  • Inflorescence: Solitary, axillary, or cymose as in Solanum
  • Flower: bisexual, actinomorphic
  • Calyx: sepals five, united, persistent, valvate aestivation.
  • Corolla: petals five, united valvate aestivation Androecium: stamens five, epipetalous
  • Gynoecium: carpellary, syncarpous ovary superior, bilocular, placenta swelled with many ovules.
  • Fruits: berry or capsule
  • Seeds: many, endosperms
  • Floral Formula:
  • Economic Importance: Many plants belonging to this family are sources of food (tomato, brinjal, potato), spice (chili) medicine (belladonna, ashwagandha) fumigatory (tobacco) ornamentals (petunia).

Question 11.
Describe the various types of placentations found in flowering plants.
Answer:

  1. The flower is a condensed shoot which is specialised to take part in sexual reproduction of angiosperms.
  2. Part of Flower. A flower is generally raised above the point of origin by means of a stalk called a pedicel. Base of flower is broadened to accommodate all the components. It is called thalamus.
  3. It has condensed nodes and internodes. The various parts of the flower are called floral organs. They are of four types – sepals, petals, stamens and carpels.
  4. Sepal or Calyx. They are green, foliaceous outermost and lowermost floral organs. They can be free (polysepalous) or fused (gamosepalous). An extra whorl of green bracts called epicalyx occurs in many members of the family Malvaceae.
  5. The major function of sepals is protection and support to other floral organs. Petals or Corolla. They are brightly coloured flat leaf-like floral organs which lie inner to sepals and outside the stamens.
  6. Petals may be free (polypetalous) or fused (gamopetalous). Their major function is to attract pollinating animals.
  7. Stamens or Androecium. They are male reproductive organs or microsporophylls of a flower. Stamens may be borne directly over the thalamus or attached to petals (epipetalous).
  8. Stamens can be free or fused by their filaments (adelphous condition), anthers (syngenesious) or both (synandrous).
  9. Each stamen has a thread-like stalk or filament and knob-like anther. Anther is bilobed and tetrasporangiate. Pollen grains are formed inside the sporangia of anther.
  10. Carpels or Gynoecium. They are mega- sporophylls or female reproductive organs of the flower. Carpels may be free (apocarpous) or fused (syncarpous).
  11. It has three parts – stigma, style and ovary. Stigma is the terminal part of the pistil which is specialized to receive and nourish the pollen grains. Style is a stalk that raises the stigma above the ovary.
  12. Ovary is the basal swollen part which internally bears ovules over the placenta. Ovules later ripen to form seeds while ovary develops into a fruit.

Question 12.
What is a flower? Describe the parts of a typical angiosperm flower.
Answer:
A flower is a reproductive unit in angiosperms:
It is meant for sexual reproduction. A typical flower has four different kinds of whorls arranged successively on the swollen end of the stalk or pedicel, called thalamus or receptacle. These are calyx, corolla, androecium and gynoecium.

Calyx:
The calyx is the outermost whore of the flower and the members are called sepals.
Generally, sepals are green leaf-like and protect the flower in the bud stage. The calyx may be gamosepalous (sepals united) or polysepalous (sepals free).

Corolla:
Corolla is composed of petals. Petals are usually brightly colored to attract insects for pollination may be free or united. The shape and colour of corolla vary greatly in plants. Corolla may be tubular, bell-shaped, funnel-shaped or wheel-shaped.

Androecium:
The androecium is composed of stamens. Each stamen which represents the male reproductive organ consists of a stalk or a filament and an anther. Each anther is usually bilobed and each lobe has two chambers, the pollen sacs. The pollen grains are produced in pollen-sacs. When stamens are attached to petals, they are epipetalous as in brinjal or epiphyllous when attached to perianth as in the flowers of lily. The stamens may be united into one bundle (monadelphous) as in China rose, or two bundles (diadelphous) as in pea, or into more than two bundles (polyadelphous) as in citrus.

Gynoecium:
The gynoecium is the female reproductive part of the flower and is made up of one or more carpels. A Carpel consists of three parts namely stigma, style, and ovary. The ovary is the enlarged basal part, on which lies the elongated tube, the style. The style connects the ovary to stigma. The stigma is usually at the tip of the style and is the receptive surface for pollen grains. Each ovary bears one or more ovules attached to a flattened, cushion-like placenta.

Question 13.
How do the various leaf modifications help plants?
Answer:

  • Leaves are often modified to perform functions other than photosynthesis.
  • They are converted into tendrils for climbing as in peas or into spines for defence as in cacti.
  • The fleshy leaves of onion and garlic store food. In some plants such as Australian acacia, the leaves are small and short-lived.
  • The petioles in these plants expand, become green and synthesise food.
  • Leaves of certain insectivorous plants such as pitcher plant, venus-fly trap are also modified leaves and get nitrogen from prey.

Question 14.
Define the term inflorescence. Explain the basis for the different types of Inflorescence in flowering plants.
Answer:
The arrangement of flowers on the floral axis is termed an inflorescence. Depending on whether the apex gets converted into a flower or continues to grow, two major types of inflorescences are defined-racemose and cymose. In the racemose type of inflorescences, the main axis continues to grow, the flowers are borne laterally in acropetal succession. In the cymose type of inflorescence the main axis terminates in a flower, hence is limited in growth.

Question 15.
Write the floral formula of an actinomorphic, bisexual, hypogynous flower with five united sepals, five free petals, five free stamens and two united carpels with superior ovary and axile placentation.
Answer:

Question 16.
Describe the arrangement of floral members in relation to their insertion on the thalamus.
Answer:

  1. Based on the position of calyx, corolla and androecium in respect of the ovary on the thalamus, the flowers are described as hypogynous, perigynous and epigynous.
  2. In the hypogynous flower, the gynoecium occupies the highest position while the other parts are located below it. The ovary in such flowers is said to be superior, e.g., Mustard, China rose etc.
  3. If gynoecium is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous.
  4. The ovary here is said to be half inferior e.g., Pea (disc-shaped perigynous), Plum (cup-shaped perigynous).
  5. In an epigynous flower, the thalamus grows upward enclosing the ovary completely and getting fused with it, the other parts of the flower arise above the ovary.
  6. Hence, the ovary is said to be inferior as in flowers of guava and cucumber and the ray florets of sunflower.

1st PUC Biology Plant Kingdom Additional Questions and Answers

1st PUC Biology Plant Kingdom One Mark Questions

Question 1.
Garlic is a good example of
Answer:
bulb

Question 2.
A good example of a stolon bearing plant is
Answer:
Jasmine.

Question 3.
Bombax (silk cotton) is a good example of
Answer:
multifoliate compound leaf.

Question 4.
Name the kind of phyllotaxy in Hibiscus.
Answer:
Alternate phyllotaxy.

Question 5.
Name two plants that produce rhizome.
Answer:
Ginger, Turmeric.

Question 6.
What is heterophylly?
Answer:
Heterophylly refers to the presence of leaves of more than one shape on a plant.

Question 7.
What is a cladode?
Answer:
Cladode is a phylloclade of one or two ‘ internodes.

Question 8.
What is pulvinus?
Answer:
The swollen leaf base is called a pulvinus.

Question 9.
Define morphology.
Answer:
Morphology is the branch of science or biology that studies the external features of an organism.

Question 10.
What are adventitious roots?
Answer:
Adventitious roots are those roots which arise from any part of the plant, other than the radicle.

Question 11.
What are tendrils?
Answer:
Tendrils are slender, spirally coiled structures that help the weak-stemmed plants to climb on the support.

Question 12.
What is a leaf lamina?
Answer:
The leaf lamina is the green expanded part of the leaf with veins and veinlets.

Question 13.
What is a bract?
Answer:
Bract is a reduced leaf-like structure found at the base of the pedicel of a flower.

Question 14.
What is a staminode?
Answer:
Staminode is a sterile stamen, that does not produce pollen grains.

Question 15.
What are parthenocarpic fruits?
Answer:
Parthenocarpic fruits are those fruits which develop without fertilization of the ovary

1st PUC Biology Plant Kingdom Two Marks Questions

Question 1.
How is a stolon different from a sucker in plants? Give an example of each.
Answer:

Stolon Sucker
It is an aerial branch of the stem that bends down and touches the ground It is a branch of a stem arising from the underground part of the main stem
When the tip is buried in the soil, buds produce adventitious roots above the ground Eg: Jasmine It grows horizontally under the ground and produces a leafy shoot Ex: Chrysanthemums

Question 2.
What is a root cap? What is its function?
Answer:
The root cap is the thimble-like structure that covers the root apex/tip. It protects the tender apex of the root as it penetrates through the soil.

Question 3.
What are nodes and internodes?
Answer:
Nodes are the regions on the stem where leaves arise. Internodes are the regions on the stem between two nodes.

Question 4.
What is a petiole? Mention the function of the petiole.
Answer:
The stalk of the leaf is called a petiole
Functions:

  • It helps to hold the leaf blade to the light
  • It also helps the blade to flutter in wind.

Question 5.
What is a seed? What are the two major parts a seed consists of?
Answer:
A fertilised and mature ovule is called a seed. A seed has two parts.

Question 6.
What are trimerous flowers? Which group of plants has trimerous flowers?
Answer:
Trimerous flowers are those where the floral appendages are in threes or multiples of three. Monocotyledonous plants generally have trimerous flowers.

Question 7.
What are coleoptile and coleorhiza?
Answer:

  • Coleoptile is the sheath that covers and protects the plumule fn cereal grains.
  • Coleorhiza is the protective sheath of the radicle in cereal grains.

Question 8.
What is the Aleurone layer? Where is it found?
Answer:
Aleurone layer is a layer of cells rich in proteins, that separates the embryo from the endosperm in cereal grains like rice, maize, wheat, etc.

Question 9.
What is endosperm? Name two plants where endosperm is absent.
Answer:
The endosperm is the tissue that stores food materials for the developing embryo, it develops as a result of triple fusion in double fertilization. The endosperm is absent in

Question 10.
Name the plant and its family, from which colchicine is obtained.
Answer:
Colonicine is obtained from Colchicum autumnale. The plant belongs to the family Liliaceae.

1st PUC Biology Plant Kingdom Three Marks Questions

Question 1.
How are plants classified based on their life span? Give an example each?
Answer:
Based on the life-span, plants are classified into

  • Annuals – plants which complete their life-cycle in one season eg: mustard, sunflower
  • Biennials- plants which complete their life-cycle in two seasons
    eg: radish, beetroot
  • Perennials – plants which live for a number of years and produce flowers and fruits at specific seasons every year eg: mango, tamarind.

Question 2.
Define venation. Differentiate between reticulate and parallel venation.
Answer:
Venation refers to the arrangement of veins and veinlets on the lamina of leaf

Reticulate venation Parallel venation
The midrib & other branches of veins are irregularly distributed to form a network The veins run parallel to one another and no net­work is formed on the lamina
It is characteristic of dicot plants It is characteristic of monocot plants

Question 3.
How is marginal placentation different from parietal placentation? Give an example of each.
Answer:

Marginal placentation Parietal placentation
It is found in the monocarpellary, unilocular ovary. It is found in syncarpous ovaries.
Placentae are found along the ventral suture, formed by the fusion of margins of a carpel. eg: pea, bean carpels are fused laterally and the placentae develop on the ovary wan as many as numbers of carpels eg: cucurbits, mustard.

Question 4.
What is a floral diagram? Describe.
Answer:
A floral diagram is the diagrammatic representation of the ground plan of a flower. It provides information about.

  • The number of floral parts
  • Their arrangement and interrelationships among various floral parts

The position of the mother axis with respect to the flower is indicated by a dot on top of the floral diagram – calyx, corolla, androeium and gynoeium are represented in successive whorls with calyx being the outermost.

Question 5.
What is pneumatophore? How do they help the plant? Name an example.
Answer:
Roots that grow vertically upwards and come” above the soil surface are called pneumatophores. They bear openings called pneumatophores for the exchange of gases.

This feature is an adaptation for plants growing in marshy/swampy areas, where oxygen is deficient in the soil. These roots help the plants to get oxygen from the air for respiration. Eg: Rhizophora.

1st PUC Biology Plant Kingdom Five Marks Questions:

Question 1.
What are herbs, shrubs, and trees among plants? Give an example for each. What is the criterion for this classification?
Answer:
(a) Herbs: They are small seasonal plants with soft stem
Eg: Mustard

(b) Shrubs: They are medium-sized plants with woody stems that branch profusely from the base and attain a bushy appearance
Eg: Rose

(c) Trees: These are plants with a short and tall trunk with profuse branching.
Eg: Mango, Neem. Plants are classified on the basis of height and strength of stems.

Question 2.
What is a flower? Describe the parts of a typical angiosperm flower.
Answer:
A flower is a modified shoot, meant for reproduction in angiosperms. A typical flower has a stalk called pedicel and four different kinds of appendages arranged in successive whorls on the swollen end of the axis called the thalamus. The outermost whorl is the calyx and consists of sepals. The next inner whorl is the corolla and consists of petals. The third whorl is the androeium which is composed of stamens. The fourth and innermost whorl is the gynoecium which is composed of carpels. The calyx and corolla are called accessory whorls and the androeium and gynoecium are called essential reproductive whorls.

Question 3.
Describe vexillary aestivation along with a diagram name an example.
Answer:
It is found in papilionaceous corolla. The posterior vexillum or standard petal is completely external and overlaps the two lateral wing petals.

The other margin of each of the wing petals overlaps the margin of the keel petals. Keel petals are the smallest and anterior and their other margins are fused together.
Eg: Pea, Bean

Question 4.
Write five differences between a dicot seed and a maize grain.
Answer:

Dicot seed Maize Grain
It is a seed that has developed from the ovule It is a single-seeded fruit, the ovary modified
The seed coat is distinct from the fruit wall The seed coat is completely fused with the pericarp single cotyledon
Two cotyledons Endosperm is absent Single cotyledon Endosperm is present
There is no proactive sheath for the plumule and radicle The plumule is protected by coleoptile and radicle by coleorhiza

Question 5.
Name one plant of Fabaceae, that yields each of these:
Answer:


CBSE Class 11 Biology Chapter 5 Morphology of Flowering Plants Study Materials

The angiosperms or flowering plants show a large diversity in external structure called as morphology (Gk. Morphe—form logos—study). However, they all are characterised by the presence of roots, stems, leaves, flowers and fruits.
1. Flowering Plants
The plant body consists of a main axis, which may be branched or unbranched bearing lateral appendages.
The main axis is divided into two parts
(i) Root system The underground root system develops from the radicle embryo and helps in fixation of the plant as well as absorption of water and minerals.

(ii) Shoot system The aerial shoot system develops from the plumule embryo.
It contains root, stem, leaves as vegetative parts and flowers, fruits and seeds as reproductive parts. The Vegetative parts are involved in various vegetative functions like structural organisation, fixation, absorption, nourishment, growth and maintenance of various components and ” reproducting parts are for sexual reproduction and germination of new plants.
The Root
In plants, root is the non-green (due to absence of chlorophyll), cylindrical and descending part that normally grows downwards into the soil. It does not bear leaves, buds and not distinguished into nodes and inter nodes.
Regions of the Root
A typical root contains following five regions. However, there is no clear line of distinction between these regions.
i. Root Cap (Calyptra)
The root is covered at the apex by a thimble or cap-like structure called the root cap. It protects the root meristem from friction of the soil particles and also protect tender apex which allow the passage of root through cells, e.g., Lemna, Eichhornia.
ii. Growing Point (Meristematic) Zone
It is a small (about 1 mm in length) thin-walled region having dense protoplasm. It lies partly within and partly beyond the root cap. Its cell divide regularly and repeatedly for elongation. It is responsible for the growth of the root.

iii. Zone of Elongation
It is situated behind the meristematic region (growing point). The cells elongate speedily and increases the length of the root. The cells of this region can absorb water and minerals from the soil.
iv. Root Hair Zone
It is the region where primary tissues differentiate into the root. The vascular tissues like xylem and phloem are formed.
Root hair zone is the most important part of the root for absorption of water (most of the water) from the soil. The root hairs increase the exposed surface of the root for absorption.
v. Zone of Maturation
This zone contains mature cells. It forms the permanent zone of the root and also gives out lateral roots from the interior part of this region, e.g., In dicots and gymnosperms.
• Roots of parasitic plants lack root caps.
• In aquatic plants, root hairs are usually absent.
Types of Root System
The root system can be of two types on the basis of place of origin
i. Tap Root System
The tap root develops from the radicle of embryo of a seed. In most of the plants, primary root persists and becomes stronger to form tap root. The first root forms by the elongation of radicle and is called primary root. It continuously grows and produces lateral roots called secondary roots.
The further branches of the secondary roots are called tertiary roots and so on. These types of roots are present in dicots, e.g., Pea, gram, groundnut, etc.
ii. Adventitious Root System
The roots developing from any part of the plant other than the radicle are known as adventitious roots (L.adventitious .extraordinary). These are usually found in monocots.
The adventitious roots can be further classified as following on the basis of nature of development
(a) Fibrous Roots The primary root soon gets replaced by a cluster of slender, thread-like roots originating from the base of the stem, e.g, Triticum vulgare (wheat), Oryza sativa (rice), Allium sepa (onion).
(b) Foliar Roots These roots develop from the leaf, i.e., from the petiole of the leaf, e.g., Pogostemon, rubber plant.
(c)True Adventitious Roots These roots develop from the nodes and internodes of the stem, e.g., Prop roots of banyan (Ficus), climbing roots of money plant (Pothos), roots from the stem when partially immersed in water (Coleus), roots from nodes (Oxalis repens) etc.

Modification of Roots
The modifications are the changes in shape, form or structure in an organ to carryout special function other than or in addition to the normal functions. Modification of roots are found in both tap roots ancf adventitious roots.
Modification of Tap Roots
The tap roots are modified for the function like storage, nitrogen-fixation and respiration.
(a) Conical Roots These are fleshy tap roots that resemble a cone (broad at the base and gradually tapering towards the apex), e.g., carrot (Daucus carotd).
(b) Fusiform Roots The primary root is spindle-shaped. It is swollen in the middle and gradually tapers at both the ends, e.g., Radish (Raphanus sativus).
(c) Napiform Roots The primary root is almost spherical (pitcher-shaped) at the base and tapers abruptly at the lower end, e.g., – beetroot (Beta vulgaris),-turnip (Brassica rapa), etc.
(d) Tuberous Roots The primary root becomes thick and fleshy but do not attain any definite shape (irregularly-shaped), e.g., 4 O’clock plant (Mirabilis jalapd), Echinocystis lobata.

(e) Nodulated Tap Roots In this the secondary, tertiary and sometimes primary roots bear many small irregular swellings called root nodules which contain countless, minute nitrogen fixing bacteria of the genus Rhizobium, e.g., groundnut (Arachis bypogea), clover (Medicago falcata), pea (Pisum sativum), etc.
(f) Pneumatophores These are special roots that develop in mangrove plants (grow in marshy areas). The pneumatophores or aerophores or respiratory roots grow vertically upward and are negatively geotropic.
They have minute breathing pores called pneumatophores or lenticels present on the tips of vertical roots that help in getting oxygen for respiration.
Modification of Adventitious Roots
The adventitious roots are modified to perform several additional functions like food storage, mechanical support and other vital functions.
(a) Fasiculated Roots These arises in clusters from the base of the stem, e.g., Dahlia, Asparagus.
(b) Nodulous Roots These roots have swellings occur only near the tips, e.g., Arrow root (Maranta), amia haldi (Curcuma amadd).
(c) Tuberous Roots (Single Root Tubers) These are swollen without any definite shape, e.g., Ipomoea batatas (sweet potato).
(d) Prop (Pillar) Roots The prop roots grow as the horizontal branches of the stem and grow vertically downward.
They become thick pillar-like and provide mechanical support to the giant trees, e.g., Banyan tree (Ficus benghalensis).

(e) Stilt Roots These are small thick supporting roots growing obliquely from the basal nodes of the main stem. These provide mechanical support, e.g., Saccharum officinarum (sugarcane), Zea mays (maize).
(f) Climbing (Clinging) Roots These roots are found in climbers. They may arise from the nodes, e.g., Ivy, Pothos (money plant).

(g) Assimilatory (Photosynthetic) Roots These roots have chlorophyll and can synthesise food, e.g., Aerial or hanging roots of some orchids.
(h) Parasitic (Sucking) Roots These roots occur in parasitic plant for absorbing nourishment from their host. These roots function as haustoria, e.g., Cuscuta (dodder).
Functions of Roots
The major functions of roots are as follows
(i) Fixation Root provides fixation to the plants with soil.
(ii) Absorption Roots absorb water and minerals from the soil and provide it to all parts of the body.
Storage Roots of many plants store food for the use of other plant parts and for animals.
(iv) Aeration Plants growing in waterlogged soil or marshy areas have special roots, i.e., pneumatophores for respiration.
(v) Conduction Roots transport water and minerals in upward direction for the uses of stems and leaves.
The Stem
The stem is the ascending part of the axis bearing branches, leaves, flowers and fruits. It develops from the plumule of the embryo of a germinating seed.
It shows distinction into nodes and internodes where node is the region from where leaves are born and internodes are the region between two nodes. Its apex bears a terminal bud for growth in length.
A bud can be defined as a condensed embryonic shoot that has a growing point surrounded by closely packed immature leaves. When bud grows, the internodes become longer and the leaves spread out, resulting in the formation of a young shoot.
Note:
* The largest bud is cabbage.
* Bamboo is considered to be tallest herb, tallest shrub or arborescent grass. Bamboos are called culms, after the jointed nature of their stems.
Forms of Stem
Stem may be aerial, subaerial or underground. In most of the plants, stems grow above the soil. These are aerial stems. The aerial stems of some plants trail or creep on the ground. They are called subaerial stems. In some plants, the stem grow in the soil and are called underground stems.
i. Aerial Stems
The aerial stems have two forms, i.e., reduced stem and erect stem.
(a) Reduced Stems It is reduced to a small disc. The * nodes and internodes are not distinguished, e.g., carrot, radish, turnip, etc. In some aquatic plants, the reduced discoid stem is green and flattened to float on the surface of water. It does not bear leaves, e.g., Lemna, Wolffia, Spirodela. In underground structures also a reduced, non-green stem is found, e.g., Garlic, onion and lily.
(b) Erect Stems These stems are strong enough to remain erect or upright without any external support.
ii. Subaerial Stem
In subaerial stems, some part lives underground, whereas, the remaining part of the stem is aerial.
The subaerial stem are also divided into two forms
(a) Upright Weak Stems These stems are weak which climb up a support to expose their foliage and reproductive organs.
These are of two types twiners and climbers
* Twiners These are long, slender and very sensitive and coil around an upright support on coming in contact, e.g, Dolichos lab lab (bean), Clitoria (butterfly pea), Cuscuta.
* Climbers These have weak and flexible stem which climb up a support with the help of certain clasping or clinging structures, e.g., Bougainvillea.
(b) Prostate Weak Stems These weak stems take support of the ground for spreading as growth occurs.
They are of following four types
* Trailers (creepers) They trail along the surface and do not climb up.
* Runners These are subaerial weak stems that grow horizontally along the soil surface, e.g., Cynadon (lawn grass), Centella (brahmi booti), Oxalis, etc.
* Stolons These subaerial weak stems are horizontal or branched runners with long internodes which can pass over small obstacless. Stolons, also propagate vegetatively like runners, e.g, Fragaria verica (strawberry), Jasminum (jasmine), Mentha piperita (peppermint).
* Offsets These weak stems are one internode long, stout, slender and runs horizontally and terminates in a bud at a short distance that develops into adventitious roots, e.g., Pistia (water lettuce), Eichhomia (water hyacinth), etc.
iv. Underground Stems
The stem of some plants lie below the soil surface. They are non-green, store food as means of perennation and vegetative propagation.
They are of following types
(a) Rhizome It is a prostrate thick stem growing horizontally beneath the soil surface. It has distinct nodes and internodes. The. nodes bear small scale leaves with buds in their axils, e.g., Zingiber (ginger officinale), Curcuma domestica (turmeric).
(b) Suckers These are non-green slender stem that grows horizontally in the soil and ultimately comes out to form a new aerial shoot. Each sucker contains one or more nodes with scale leaves and axillary buds, e.g., Mentha (podina), Chrysanthemum (guldaudi).
(c) Corm It is a swollen condensed form of rhizome which grows in the vertical direction in the soil. It stores a large amount of food, e.g., Amorphophallus, Colocasia (taro).
(d) Tuber It is a swollen end of underground stem branches. Each tuber has many notches on the surface called eyes or buds, which grow into new plants, e.g, Solanum tuberosum (potato).
(e) Bulb It is a highly reduced disc like stem. It bears a large number of fibrous adventitious roots at its base. Leaf bases form bulblets. The bulblets grow into new plants, e.g., Allium cepa (onion), Allium sativum (garlic).
Branching Pattern of Stem
The stems may be branched or unbranched.
Branching in stems may be dichotomous and lateral.
(i) The dichotomous branching occurs by the division of the apical growing point or bud into two equal parts in a forked manner. It occurs in lower plants-cryptogams (non-flowering plants), higher plants

Hyphaene (palm), Canscora, screw pine, etc.
(ii) The lateral branching occurs from the axillary buds of the nodes, e.g., Pinus, grapevine, etc.
Functions of Stem
Stems perform various primary and secondary functions.
Primary Functions
(a) It bears leaves, fruits, flowers and seeds in position.
(b) It conducts water and minerals to roots, leaves, flowers, fruits, etc.
(c) It holds flower in suitable position, so that pollination and fertilistaion takes place.
Secondary Functions
(a) Many stems store food as reserve food materials.
(b) Some stems also help in photosynthesis and vegetative propagation.
(c) The underground stems help in perennation.
(d) Stem branches provide support to its various parts.
Modification of Stem
The various forms of aerial stem modification are following
i. Stem Tendrils
These are thin, long and sensitive structures which can coil around a support.
Tendrils can be of following types on the basis of their origin (d) Axillary Arise from axiallary buds, e.g., Passiflora (passion flower).
(b) Extra axillary Develop near the axillary bud, e.g., Lujfa, Cucurbita (pumpkin), etc.
(c) Apical bud These are modified to form tendrils, e.g., Vitis vinifera.
(d) Floral bud These are modified to form tendrils, e.g., Antigonon.
Stem Thorns
The stem thorns are stiff, woody, sharp and pointed. They develop from axillary bud. They protect the plants from browsing animals, e.g., Citrus, Duranta, Bougainvillea, Pomegranate, etc.
Prickles
These are modified stems and act as climbing organs. They protect the plants from grazing animals and also help in climbing in some cases, e.g., Argemone maxicana (prickly poppy), Rosa indica (rose), Bombax (sembal), etc.
Phylloclade
These are green, flattened structures bearing several nodes and internodes. The true leaves are reduced to spines or scales. They show unlimited growth. Some phylloclades also store food and water. The phylloclades are examples of some xerophytic plants, e.g., Opuntia (nagaphani), Casuarina, Euphorbia.
Cladodes (Cladophylls) .
They are green photosynthetic stems generally one inter node long. These develop by the modification of only stem branches of limited growth and are green (photosynthetic). The true leaves of the plant are reduced to scales or spines, e.g., Ruscus, Asparagus.
ii. Bulbils
These are modified vegetative or floral buds arising in the axil of scale or foliage leaves. The bulbil helps in vegetative propagation, e.g., Lilium, Agave, Dioscorea (wild yam), Oxalis, etc.
The Leaf
The leaf is a lateral, generally Battened structure borne on the stem. It develops at the node and bears a bud in its axil. The axillary bud later develops into a branch. Leaves originate from shoot apical meristems and are arranged in an acropetal order. They are the most important vegetative organs for photosynthesis.
Parts of a Leaf
The leaves also consist of two lateral outgrowths called stipules at their bases.
A typical leaf has three main parts.
i.Leaf Base (Hypopodium)
The leaf is attached to the stem by the leaf base. Monocots, the leaf base is said to be sheathing as it expands and partially and wholly surrounds the stem. In dicots, the leaf base bears two lateral outgrowths called stipules.
In some leguminous plants, the leaf base may become swollen which is called the pulvinus. Leaves with stipules are called stipulate and those without them are termed as exstipulate.
ii. Petiole (Mesopodium)
It is the stalk of a leaf. Petiole help hold the leaf blade towards light. Petiole raises the lamina high to the level of stem so as to provide maximum required exposure to light and air.
iii. Lamina (Epipodium)
The lamina or leaf blade is the green, expanded part of the leaf with veins and veinlets. It has a prominent median vein called the midrib. It produces thinner lateral veins which in turn branch to form veinlets.
The lamina is the seat of photosynthesis, gaseous exchange, transpiration and other metabolic activities. The shape, margin, apex, surface and extent of invision of lamina varies in different leaves.

Venation
The arrangement of veins and veinlets in the lamina of leaf is called venation. The midrib, veins and veinlets are contain vascular tissues, i.e., The xylem and phloem for conduction water, mineral salts and food.
Leaves have mainly two types of venation
i. Reticulate Venation
When the veinlets form a network, the venation is called reticulate. It is found in dicot leaves. However, some monocot leaves like Smilax, Dioscorea and Alocasia also show reticulate venation.
ii. Parallel Venation
When the veins run parallel to each other within a lamina, the venation is termed as parallel, e.g. Calophyllum, Zingiber officinale, etc.

Types of Leaves
Leaves can be of following types
i. Simple Leaves
A leaf having a single or undivided lamina is called simple leaf. The lamina of a simple leaf may be incised but the incisions do not touch the midrib.
The lamina can have various types of incisions which may reach upto half (fid), more than half (partite) or near the base or midrib (sect).

Compound Leaves
A leaf is called compound when the incision of the leaf blade goes down to the midrib (rachis) or to the petiole so that the leaf is broken up into a number of segments called leaflets.
A bud is present in the axil of petiole in both simple and compound leaves but not in the axil of leaflets of the compound leaf.
A compound leaf can be of following two types
(a) Pinnately Compound Leaves In these leaves, the incision of lamina is directed towards the midrib, which is known as rachis. Leaflets are arranged on both side on the rachis, e.g., Neem, rose, etc.

(b) Palmate Compound Leaves The leaflets are attached at a common point, i.e., at the tip of petiole as in silk cotton.

Phyllotaxy
The pattern of arrangement of leaves on the stem or branch is called phyllotaxy. It helps to avoid overcrowding and provide every leaf with optimum sunshine.
Phyllotaxy is usually of three types
i. Alternate (Spiral) Phyllotaxy
A single leaf arises at each node in alternate manner, e.g, China rose, mustard and sunflower plants.
ii. Opposite Phyllotaxy
A pair of leaves axises at each node and opposite to each other, e.g., Calotropis and Psidium guajava (guava plants).
Whorled (Verticillate) Phyllotaxy
If more than two leaves arise at a node and form a whorl, it is called whorled. The leaves of one whorl generally alternate with those of the adjacent whorls in order to provide maximum exposure, e.g., Nerium (kaner), Alstonia.

Modification of Leaves
Leaves of plants are modified to perform different additional functions in addition to their main function, i.e., photosynthesis.
i. Leaf Tendrils
These are thread-like sensitive structures, which can coil around a support to help the plant in climbing, e.g, Wild pea (Lathyrus aphaca), Pisum sativum (sweet pea) and Gloriosa superba (glory lily). ”
ii. Phyllode
It is a green, short lived and flattened petiole or rachis of a leaf, which performs the function of photosynthesis, e.g, Australian Acacia. Phyilodes develop usually vertically and possess fewer stomata hence, reduce transpiration.
iii. Bladder
The segments of the leaf modify into bladder-like structures, which trap small insects present in the water. e.g., Bladderwort (Utricularia).
iv. Pitcher
It is a petiole modified into a tendril to hold the pitcher upright. The leaf base is expanded to carry out photosynthesis. The leaf apex is modified into a lid, e.g, Nepenthes, Dischidia and Sarracenia.
v. Leaf Spines
The entire leaf or a part of a leaf may be modified into a pointed structure called a spine, as in Opuntia.
vi. Scale Leaves
These are thin, membranous leaves found at the nodal region. Each scale leaf contains an axillary bud in its axil, e.g, Zingiber officinale (ginger).

Functions of Leaves
The leaves have many primary and secondary functions.
Primary Functions
(a) The most important function of leaves is photosynthesis with the help of sunlight and carbon dioxide.
(b) Leaves contain stomata through, which gaseous exchange occurs,
(c) Leaves are the site of transpiration.
(d) They protect axillary and terminal bud from mechanical injury and desiccation.
Secondary Functions
(a) Leaves store food as in the leaf base, e.g., Onion.
(b) Leaves change into phyilodes to protect against transpiration.
(c) Storage of water in the cells of some succulent plants, e.g., Aloe.
(d) In Salvinia, one leaf of each node is changed into roots that act as balancer for floating.
(e) In some leaves like of Euphorbia, the young leaves are brightly coloured to attract insects for pollination.
The Inflorescence
The arrangement and distribution of flowers over a plant is called inflorescence.
The inflorescence can be of following three types
1. Racemose Inflorescence
In racemose type of inflorescence, the main axis continues to grow and the flowers are borne laterally in an acropetal succession (the older flowers are found towards the base and younger ones at the apex) or centripetal (older towards periphery and younger towards centre).

2. Cymose Inflorescence
In cymose inflorescence, the tip of the main axis terminates in a flower and further growth continues by one or more lateral branches, which also behave like the main axis.
The arrangement of flowers in either basipetal (younger flowers occupy basal position, while older flowers towards the apex) or centrifugal (older towards center and younger towards periphery).

3. Special Inflorescence
It mainly involves highly modified and densely crowded inflorescences.
The special type of inflorescence can be divided into following types
i. Cyathium
It is highly reduced and is a cup-shaped involucre of five bracts having nectariferous glands. A single large female flower is present in the centre of the cup and scorpioid male flowers surrounded this female flower. Every male flower is represented by a single stalked stamen borne in the axil of a scaly bract, e.g, Euphorbia.
ii. Verticillaster
These are two clusters each having 3-9 flowers that develop on a node in the axils of opposite leaves, e.g., Ocimum sanctum (basil).
iii. Hypanthodium
In this type, the main axis is condensed into a cup or flask-shaped, fleshy receptacle. It bears three kinds of flowers, i.e., male flowers (towards the pore), female flowers (towards the base) and neutral flowers occurs in between male and female flowers, e.g., Peepal (Ficus relegiosa) and banyan (Ficus benghalensis).
The Flower
The flower is the reproductive unit in the angiosperms. It is meant for sexual reproduction. Morphologically, it is considered as a shoot bearing nodes and modified floral leaves. A flowers is called modified shoot because the position of the buds of both flower and shoot which is same and can be in terminal or axillary in position.
Structure of Flower
A flower arises in the axil of a leaf like structure called bract. Flowers with bracts are called bracteate and those without bracts are called ebracteate.
The terminal part of the axis of the flower is the receptacle or thalamus. The receptacle contains sepals, petals, stamens and carpels. If the leaves are present on the pedical, they are called bracteoles.

Parts of a Flower
A typical flower consists of four distinct parts the calyx, the corolla, the androecium and the gynoecium. The calyx and corolla are accessory parts and the androecium and gynoecium are essential parts.
These essential parts consist of two kinds of (male) sporophylls, the microsporophyll (male) and the megasporophyll (female).
A flower can be unisexual or bisexual. It is borne on short or long axis. The axis contains two regions the pedicel and the thalamus or receptacle.
The pedicel may be short, long or even absent. The thalamus is the swollen end of the axis on which the floral whorls are arranged.
Different parts of flower are given below
i. Calyx
It is the outermost whorl of a flower. It is made up of units like sepals. The sepals are generally green, leaf like and protect the flower in the bud stage, i.e., when floral in bud condition. They have veins and stomata like ordinary leaves but are thicker in nature. The sepals may be gamosepalous (sepals united), e.g., Caesalpinia or polysepalous (sepals free), e.g., Crotalaria.
The sepals also prevent transpiration from inner parts of the flower. Coloured sepals attract insects for pollination.
ii. Corolla
It is composed of petals. Petals are usually brightly coloured to attract insects for pollination. Like calyx, corolla may also be gamopetalons (petals united) or polypetalous (petals free). The shape and colour of corolla may vary greatly in shape. Corolla may be tubular, bell-shaped, funnel-shaped.
Aestivation
The mode of arrangement of sepals or petals in floral bud with respect to the other members of the same whorl is known as aestivation. The aestivation pattern is important in classification of – plants.
It is of following types
(a) Valvate Petals come to each other but do not overlap, e.g., mustard (Brassica).
(b) Twisted Regular overlapping of petals occurs in which margin of one petal overlap with the next one petal, e.g., China rose (Hibiscus rosa sinensis).
(c) Imbricate There are five petals, arranged in such a way that one petal is completely external and another petal is completely internal, while three petals are partially external and partially internal, e.g., Cassia, Cullistemon,Caesalpinia.
(d) Vexillary When the largest petal overlaps the two lateral petals which in turn overlap the two smallest anterior petals (keel), the aestivation is called as vexillary or papilionaceous.

iii.Androecium
It is the third whorl of flower composed of stamens or microsporangium. Each stamen, which represents the male reprodutive organ consists of a stalk or a filament and an anther. Each anther is usually bilobed which are attached at the back by a sterile band called connective and each lobe has two chambers, the pollen sacs. The pollen grains are produced in pollen sacs. A sterile stamen is called staminode. Stamens can be of different types depending on their union with other members such as petals or among themselves.
(a) When stamens are attached to the petals, they are epipetalous, e.g., Brinjal.
(b) When stamens are attached to the perianth, the condition is called epiphyllous, e.g., Lily.
(c) The stamens in a flower may either remain free, i.e., polyandrous or may be united in varying degrees.
(d) The stamens may be united into one bunch or one bundle, i.e., monoadelphous as in China rose. It may be two bundles, i.e., diadelphous as in pea or into more than two bundles, i.e., polyadelphous as in citrus.
(e) There may be variation in the length of filament as in Salvia and mustard.
iv. Gynoecium
Gynoecium is the female reproductive part of the flower and is made up of one or more carpels or megasporangium. Megaspores are produced within the megasporangium.’A carpel consists of three parts, i.e., stigma, style and ovary.
The stigma is usually at the tip of style and is the receptive surface for pollen grains.
Ovary is the enlarged basal part on which lies the elongated tube, the style.
The style connects the ovary to the stigma. Each ovary bears one or more ovules attached to a flattened, cushion like placenta.
Depending on the number of carpel present may be free or united, gynoecium can be of following types
(a) Apocarpous When more than one carpel is present, they may be free are called apocarpous, e.g., Lotus and rose.
(b) Syncarpous When carpels are fused together, the gynoecium is called syncarpous, e.g., Brinjal and Hibiscus.
The cavity enclosed by the ovary wall is called locule. The number of locules in the ovary correspond to the number of carpels in the gynoecium, i.e., unilocular (only one locule, e.g., Pea), bilocular (two locules, e.g., Tomato), trilocular (three locules, e.g., Ricinus), multilocular (many locules, e.g., Orange and lemon).
The arrangement of ovules within the ovary is known as placentation. The placenta is a tissue, which develops along the inner wall of the ovary. The ovule or ovules remain attached to the placenta.
The placentation can be of different types
(а) Marginal The placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows is called marginal placentation, e.g., Pea.
(b) Axile When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is called axile, e.g., China rose, tomato and lemon.
(c) Parietal When the ovules develop on the inner wall of the ovary or on peripheral part, it is called parietal placentation. Ovary is one chambered but it becomes two-chambered due to formation of the false septum, e.g., Mustard and Argemone.
(d) Free central When the ovules are borne on central axis and septa are absent, the placentation is called free central, e.g., Dianthus and primrose.
(e) Basal In this type, the placenta develops at the base of ovary and a single ovule is attached to it as in sunflower, marigold. The placenta develops directly on the thalamus.

Insertion of Floral Parts (Forms of Thalamus)
The positions of different whorls of flowers are different. This is due to the position of ovary.
These positions may be of three types
i. Hypogynous Flower
The thalamus is conical, dome-shaped or flat. The ovary is present at the top of thalamus. The stamem, petals and sepals are separate and successively inserted below the ovary. Ovary is superior, whereas rest of the structures are inferior, e.g., Brassica, Hibiscus, Petunia.
ii. Perigynous Flower
The margin of thalamus grows upwards forming a cup like structure called calyx tube. The calyx tube encloses ovary, but remains free from it and the sepals, petals and stamens are present in it. The ovary is half inferior, e.g., rose, plum, peach, etc.
iii. Epigynous Flower
The thalamus grows upwards to completely develop the ovary and also fused inseparably with the latter. The other floral parts are borne at the top of the fused thalamus and ovary. The ovary is called inferior, e.g., Helianthus (sunflower), Cucurbita (pumpkin), Pyrus (apple).

Number of Floral Parts
When the floral appendages are in the multiple of 3, 4 or 5, the flower is considered as trimerous, tetramerous or pentamerous respectively.
Dicotyledonous flowers are usually di, tetra or pentamerous, while, monocotyledonous flowers are trimerous.
Symmetry of A Flower
The symmetry of a flower depends upon the shape, size and arrangement of floral parts, e.g., Calyx, corolla, androecium and gynoecium. Flowers can be actomorphic and zygomorphic on the basis of symmetry.
Actinomorphic
In this type, a flower can be divided into exactly equal halves by any vertical section passing through the centre of a flower, e.g., Mustard, datura.
Zygomorphic
In this type, flower can be divided into two identical halves through only one particular vertical plane, e.g., Ocimum, Cassia.
The Fruit
The characteristic feature of flowering plants is fruit. Fruit is a mature or ripened ovary, developed after fertilisation.
During fertilisation, the important changes taking place in the ovary are
(ii) The ovules present in it develops into seeds.
(ii) The wall of the ovary thickens and ripens into pericarp (fruit wall).
Note:
* Fruits developed from the fertilised ovary is called true fruits. A true fruit has two parts pericarp and the seeds.
* Fruits developed from any part of the flower along with ovary is called false fruits. The thalamus grows along with the ovary to form a false fruit i.e. in Pyrus malus (apple).
* The fruit of mango and coconut are also known as drupe, as it develop from monocarpellary superior ovaries and have only one seed.
The ovary after these changes is known as the fruit. If a fruit is formed without fertilisation, it is called parthenocarpic fruit, e.g., Banana, grapes, pineapple, etc. The parthenocarpic fruits do not have seeds.
The fruit consists of wall or pericarp and seeds. The pericarp may be dry or fleshy. When pericarp is thick and fleshy, it is differentiated into outer epicarp, the middle mesocarp and the inner endocarp.

Types of Fruits
Fruits can be broadly classified into following three types
i. Simple Fruits
A simple fruit develops from the single simple or compound ovary of a flower. These can be dry fruits (pericarp dry) or succulent fruits (pericarp fleshy).
ii. Aggregate (Etaerio) Fruits
An aggregate fruit is a group of fruitlets which develops from a flower having polycarpellary apocarpous (free) gynoecium. The aggregate fruit is also called etaerio.
iii. Multiple (Composite) Fruits
A composite (multiple) fruit develops from an entire inflorescence. The multiple fruit is composed of a number of closely associated fruits (which may or may not get fused) along with its peduncle. Hence, these fruits are pseudocarps and are also called inflorescence fruits.
Pomology is the branch of horticulture that deals with the study of fruits and their cultivation.
Edible Parts of Some Common Fruits

Importance of Fruits
(i) Fruits are a source of vitamins, organic acids, minerals, pectin and sugars and some of them are used as vegetables, e.g., Okra (lady’s finger), tomato, pumpkin, cucumber, gourd, etc.
(ii) Cereals are one seeded dry fruits, form the stable food of humans.
(iii) Fruits are important foods for fruit eating birds (frugivorous) and some animals.
(iv) Some fruits are also used as medicines, e.g., Emblica officinalis (amla), Datum stramonium (datura), Papaver somniferum (poppy), etc.
(v) They protect immature seeds against climatic conditions till their maturity.
(vi) The unripe fruits are bitter due to the presence of tannins, bitter alkaloids, astringents, sour acids, etc. This way they keep the animals away from eating them.
The Seed
Seed is a ripened ovule which contains an embryo or tiny plant with sufficient reserve food for the development of embyo.
The ovules after fertilisation develops into seeds. A seed is made up of seed coats and an embryo. The embryo is made up of a radicle, an embryonal axis and one (wheat and maize) or two cotyledons (gram and pea).
Types of Seeds
Seeds can be classified into two different types based on the number of cotyledons and presence or absence of endosperms, i.e., dicotyledonous and monocotyledonous seed.
i.Dicotyledonous Seed
Gram seed is a dicot seed formed in a small pod or legume. The outermost covering is the seed coat. An endosperm is absent.
Seed can be studied under two heads, i.e., external structure and internal structure.
It is light or dark brown in colour. Its surface may be smooth or wrinkled. A small oval scar present at the side called hilum. It is the point where the stalk or funicle of the seed is attached to it. A narrow ridge called raphae runs from hilum to chalaza inside the furrow. A small pore called micropyle present between the hilum and pointed end.
The outermost covering of the seed is seed coat. The outer hard and leathery layer of the coat is called testa and the inner thin and membranous layer is the tegmen. In some seeds, the tegmen and testa are fused.

The seed coat encloses the embryo, which is differentiated into a radicle, a plumule and cotyledons. The radicle develops into root and plumule into shoot. Cotyledons may be one or two to serve as reserve food.
Hypocotyl is a part present between the point of attachment of cotyledon and radicle. Epicotyle is present between point of attachment of cotyledons and plumule.
In some seeds, such as castor seeds, the endosperm is formed as a result of double fertilisation, which is a food storing tissue. In plants like bean, gram and pea, the endosperm is not present in mature seeds (i.e., non-endospermous seeds).
ii- Monocotyledonous Seed
The monocotyledonous seeds are endospermic but some as in orchids are non-endospermic. In the cereals, such as maize, the seed coat is membranous and generally fused with the fruit wall.
Structure of Monocotyledonous Seed
The endosperm is bulky and stores food. The outer covering of endosperm separates the embryo by a proteinous layer called aleurone layer. The embryo is small and situated in a groove at one end of the endosperm. It consists of one large shield-shaped cotyledon known as scutellum and a short axis with a plumule and a radicle. The plumule and radicle are enclosed in sheaths which are called coleoptile and coleorhiza respectively.
Coleoptile has a terminal pore for the emergence of first leaf during germination. The sheath is capable of growth. It helps the future shoot in passing through the soil during germination, e.g., Maize grain is whitish, yellow, violet or red in colour. It has smooth or shiny surface.
Its grain is covered with a single, thin hard covering. It is formed by the fusion of seed coat or testa and the fruit wall gr pericarp.

Semi-Technical Description of a Typical Flowering Plant
The description of a flowering plant should be brief, sequential and in scientific language. This is required to designate a plant in its appropriate taxonomic position.
The Plant can be Described Briefly in the following Way

Floral Formula
The symbolic representation of floral characters of a flower is called floral formula. For example, the floral formula ofBrassica (mustard) represented as given by

Description of this formula is Ebracteate, actinomorphic, bisexual, bimerous, calyx-4, polysepalous, in two whorls of two each corolla-4, polypetalous, cruciform, androecium-6, polyandrous, tetradynamous in two whorls, one with two, gynoecium—bicarpellary syncarpous, superior.
Symbols used in Floral Formula

Symbols for Number of Floral Parts
The number of floral parts are written at right foot of the symbol. If they are fused they are bracketed.
Some examples are given below

Floral Diagram
A floral diagram provides information about the number of parts of a flower, their arrangement and the relation, they have with one another.
The floral diagram of flower tell us about the following

In the floral diagram, the position of the mother axis with respect to the flower is represented by a dot on the top of the floral diagram.. Calyx, corolla, androecium and gynoecium are drawn in successive whorls, calyx being the outermost and the gynoecium in the centre.

Description of Some important Families
I. Family-Fabaceae
This family was earlier called Papilionoideae, a sub-family of family—Leguminosae. It is distributed all over the world.
1. system position

2. Distribution The family includes 600 genera and 13000 species. It is distributed all over the world except the Arctic regions.
3. Habit The plants are mosdy herbs, however shrubs, trees and climbers are also common.
4 Vegetative Characters
(i) Root Tap root with lateral branches. The lateral branches mostly contain bacterial nodules (with Rhizobium bacteria which fix atmospheric nitrogen).
(ii) Stem Herbaceous or woody, branched, erect or climbing.
(iii) Leaf Alternate, pinnately compound or simple, leaf base, pulvinate, stipulate, venation-reticulate.
5. Floral Characters
(i) Inflorescence Simple raceme, axillary cyme or solitary.
(ii) Flower Bracteate, pedicellate, subsessile, bisexual, mostly, irregular, zygomorphic, sometimes regular, pentamerous, hypogynous or slightly perigynous.
(a) Calyx Sepals 5, gamosepalous, imbricate aestivation.
(b) Corolla Petal 5, polypetalous, papilionac¬eous, consisting of a posterior standard, two later wings, two anterior ones forming a well (enclosing stamens and pistil), vexillary aestivation.
(c) Androecium Stamens 10, usually diadelphous [(9) +1] or monadelphous, sometimes free, polyandrous, another dithecous, basifixed (attached by its base).
(d) Gynoecium Monocarpallary, ovary superior, unilocular with marginal placentation, style bent, stigma simple and hairy.
(e) Fruit Legume (pod).
(f) Seed One to many non-endospermic.
(iii) Floral Formula


Economic Importance with Examples
Plants belonging to this family hqs their importance in the following fields
(i) Pulses and Vegetables The family is an important source of pulses and vegetables. The ^pulses are rich in proteins like gram (chana), pea (matar), field bean (bankla), cluster bean (gwar), lima bean (lobia), lentil (masoor), bean (sem), soya(soyabean), etc.
(ii) Oil Edible oils are obtained from the seeds of Arachis hypogaea (groundnut) and Glycine max (soyabean). Vegetable ghee is prepared by using the oils after hydrogenation.
(iii) Timber Dalbergia sissoo (Indian redwood),Dalbergia latifolia (Indian rose wood), are important timber yielding trees of the family.
(iv) Dye Indigofera tinctoria (indigo), Butea monosperma (flame of the forest) is used to produced red dye used as an astringent.
(v) Fodder Plants like Trifolium alexandrium (barseem), Medicago sativa, Cyamopsis tetragonoloba, etc., yield fodder for the cattle.
(vi) Fibres Crotalaria juncea (sunhemp) is used to produce fibres.
(vii) Ornamentals Some common ornamental plants are Lathyrus odoratus (sweet pea), Clitoria (butterfly pea), Lupinus, etc., are common ornamental plants.
(viii) Jewellar s Weights The seeds of Abrus precatorius (ratti) are used weight by jewellars.
(ix) Medicinal Plants The flowers of Trifolium pratense are used in whooping cough. The gum of Butea monosperma (dhak) is useful for treating dysentery and diarrhoea. There are several other examples in this family that are used as medicines.
II. Family-Solanaceae
It is a large family, commonly called as the ‘potato family, it is widely distributed in tropics, sub-tropics and even temperate zones.
1. Systematic Position

2. Distribution
The family is represented by 90 genera and 2800 species distributed in both tropical and temperate regions.
3. Habit
Annual or perennial herbs, shrubs or rarely soft wooded trees.
4. Vegetative Characters
(i) Root Usually tap roots.
(ii) Stem Herbaceous or woody, hair or prickles often present, sometimes underground tubers (Solanum tuberosum).
(iii) Leaf In vegetative parts alternate and floral regions opposite, exstipulate, simple, rarely pinnately compound as in potato and tomato.
5. Floral Characters
(i) Inflorescence Solitary, axillary or cymose as in Solarium.
(ii) Flower Bisexual, actinomorphic, ebracteate, pedicellate, pentamerous and hypogynous.
(а) Calyx Sepals 5, united, valvate aestivation, usually persistent as in brinjal, tomato, chilly, etc.
(b) Corolla Petals 5, united, valvate aestivation, rotate or tubular, rarely funnel-shaped.
(c) Androecium Stamens 5, epipetalous, alternating with, petals, inserted in corolla tube, filaments usually of unequal length, anthers bithecous.
(d) Gynoecium Bicarpellary, syncarpous, ovary superior, bilocular, placenta swollen with many ovules.
(e) Fruits Berry or capsule.
(f) Seeds Endospermic, embryo straight.

Economic: Importance with Examples
Plants belonging to the family-Solanaceae has their importance in the following fields
(i) Food The family-Solanaceae includes a number of vegetables and spice yielding plants.
For example., Solanum tuberosum (potato), Solanum melongena (brinjal), Lycopersicon esculentum (tomato), Physalis peruviana (ground cherry), Capscicum annuum (chillies), etc.
(ii) Tobacco Nicotiana tabacum and N. rustica . contain toxic alkaloid nicotine. It is used for chewing, smoking and snuff.
(iii) Medicines Atropa bellodona is used to obtain Bellodona and atropine. Bellodona is used for relieving pain and treating cough. Atropine is used for dilating eye pupil. Datura stramonium is used in asthma. Other medicinal plants are Solanum xanthocarpum, Withania somnifera, Hyoscymus niger, etc.
Ornamentals The common ornamental plants are Cestrum nocturnum (Rat-ki-Rani), Petunia hybrida, Physalis peruviana (cape gooseberry), etc.
III. Family—Liliaceae
1. Systematic Position

2. Distribution
The family—Liliaceae (lily family) includes about 250 genera and 3700 species showing world wide distribution. About 200 species are available in India.
3. Habit
Usually perennial herbs, perenating by underground rhizomes, corms or bulbs, rarely shrubs or climbers (e.g., Smilax, Gloriosa, etc).
4. Vegetative Characters
(i) Root Generally adventitious, fibrous or fleshy (e.g., Asparagus).
(ii) Stem Herbaceous or woody. In some species underground bulbs or rhizomes.
(iii) Leaves Mostly basal, alternate, linear, exstipulate with parallel venation.
5. Floral Characters
(i) Inflorescence Mostly racemose, sometimes cymose, rarely solitary.
(ii) Flower Bracteate, pedicellate, actinomorphic, incomplete, bisexual, trimerous and hypogynous.
(a) Perianth Tepal six (3 + 3), often united into tube, valvate aestivation.
(b)polyandrous, opposite to tepals, sometimes epiphyllous.
(c) Gynoecium Tricarpellary, syncarpous, trilocular with many ovules, axile placentation, rarely unilocular with parietal placentation, ovary superior, style simple with three lobed stigma.
(d) Fruit A loculated capsule, rarely a berry.
(e) Seed Endospermic, embryo curved or straight.
(f) Floral Formula by

Economic Importance with Examples
Plants belonging to this family has their importance in the following fields
(i) Food Allium cepa (onion), Allium sativum (garlic) young shoots and fleshy roots of Asparagus (shatavar) are used as vegetables.
(ii) Medicines Aloe leaves are used to cure piles, liver problems. Roots of Smilax are used as blood purifier. Raw onion is useful in constipation, diarrhoea and cholera. Dried corms of Colchicum autumnale (meadow saffron) are used against rheumatism and gout.
(iii) Ornamentals The common ornamentals are Ruscus, Yucca, Aloe, Asparagus, Gloriosa, Smilax, tulips, lilies, etc.
(iv) Fibres The fibre yielding plants of IHy family are Yucca filamentosa, Sansevieria roxburghiana, etc.


How different are these terms: Phylloclade, Phyllode, Cladophyll and Cladode? - Biology

Answer: Roots of some plants change their shape and structure and become modified to perform certain functions other than absorption and conduction of water and minerals. It is called modification of roots. Roots are modified for support, storage of food and respiration, etc.
(a) Root modification in banyan tree : In banyan tree, the root modifies to form prop roots. Prop roots arise from branches and enter the soil. Thus, they provide mechanical support to densely branched, huge trees.
(b) Root modification in turnip : The
modification of root found in turnip is napiform for food storage. The upper portion of these fleshy roots is inflated or swollen which tapers towards the lower end.
(c) Root modification in mangrove trees : In mangrove plants, i.e., plants growing in saline marshes, the branches of tap root come out of the ground and grow vertically upwards showing negative geotropism. These roots are called pneumatophores. They help to get oxygen for respiration.

Q2. Justify the following statements on the basis of external features: (i) Underground parts of a plant are not always roots. (ii) The flower is a modified shoot.

Answer: (i) Underground parts of plant are not always roots because sometimes the stem also becomes underground and gets modified into various forms to perform different functions of storage, vegetative propagation, perennation, etc. Underground modifications of stems are tuber, rhizome, corm and bulb. The underground stems can be distinguished from roots externally by the presence of nodes and internodes, axillary buds, scale leaves etc. and by absence of root cap and root hairs.
(ii) Flower is the reproductive part of the angiospermic plant and it is defined as the modified shoot because (a) like shoot, flower develops from an axillary or rarely terminal bud. (b) flowers may get modified into fleshy buds or bulbils (c) A transition from foliage leaves to floral leaves is found in Paeonia. (d) Nymphaea shows transition from sepals to petals and petals to stamens (e) In Passiflora and Cleome long intemodes occur below gynoecium and stamens.

Q3. How is a pinnately compound leaf different from a palmately compound leaf?

Answer: The compound leaves may be of two types, pinnately compound leaf and palmately compound leaf. In pinnately compound leaf, a number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf as in neem. Pinnately compound leaf may be of different types as unipinnate, bipinna te, tripinna te and decompound. In palmately compound leaf, the leaflets are attached at a common point, i.e., at the tip of petiole, as in silk cotton. Palmately compound leaf may be of different types as unifoliate, bifoliate, trifoliate, quadrifoliate and multifoliate.

Q4. Explain with suitable examples the different types of phyllotaxy.

Answer: Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. It is usually of three types – alternate, opposite and whorled. In alternate type of phyllotaxy, a single leaf arises at each node in alternate manner, as in china rose, mustard and sunflower plants. In opposite type, a pair of leaves arises at each node and lie opposite to each other as in Calotropis and guava plants.
If more than two leaves arise at a node and form a whorl it is called whorled phyllotaxy as in Alstonia.

Q5. Define the following terms: (a) aestivation (b) placentation (c) actinomorphic (d) zygomorphic (e) superior ovary (f) perigynous flower (g) epipetalous stamen

Answer: (a) Aestivation : The mode of arrange¬ment of accessory floral organs (sepals and petals) in relation to one another in floral bud is known as aestivation. The main type of aestivation are valvate, twisted, imbricate, and vexillary.
(b) Placentation : The arrangement of ovules within the ovary is known as placentation. The placentation are of different types namely, marginal, axile, parietal, basal, and free central.
(c) Actinomorphic : When flower can be divided into equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic, e.g., mustard, Datura etc.
(d) Zygomorphic : When a flower can be divided into two similar halves only in one particular vertical plane, it is said to be zygomorphic, e.g., pea, gulmohar, bean, Cassia.
(e) Superior ovary : In hypogynous flower, the gynoecium occupies the highest position while the other parts are situated below it. The ovary in such flowers is said to be superior, e.g., mustard, brinjal.
(f) Perigynous flower: If gynoecium is situated in the centre and other parts of the flower are
located on the rim of the thalamus almost at the same level, it is called perigynous. Here ovary is half superior, e.g., peach, plum.
(g) Epipetalous stamen : When stamens are attached to the petals, they are called epipetalous stamens e.g., brinjal.

Q6. Differentiate between (a) Racemose and cymose inflorescence (b) Fibrous root and adventitious root (c) Apocarpous and syncarpous ovary
Q7. Draw the labelled diagram of the following: (i) Gram seed (ii) V. S. of maize seed.

Answer: (i) Gram Seed

Explanation: (ii) V.S. Of maize seed

Q8. Describe modifications of stem with suitable examples.

Answer: Stems are modified to perform different functions. Underground stems of some plants are modified to store food in them. They also act as organs of perennation to tide over conditions unfavourable for growth. Different modifications of stem are :
(i) Underground modifications
(ii)Sub-aerial modifications
(iii)Aerial modifications
(i)Underground modifications of stem are discussed as follows:
(a)Tuber: It is the branch of main stem which accumulates or stores food in it and swells up, e.g., Solarium tuberosum (potato).
(b) Rhizome: It is a branched, prostrate horizontally growing stem having nodes and internodes. On the nodes sessile scale leaves are formed, e.g., Carina, Zingiber officinale (ginger), Curcuma domestica (turmeric) etc.
(c) Corm: This is a spherical,
branched, vertically growing thick underground stem with more diameter than length, e.g., Crocus sativus (saffron), Gladiolus, Colocasia esculenta (arvi) etc.
(d) Bulb: In bulb the stem is highly reduced and can be seen only as a disc-like structure bearing numerous fleshy scaly leaves, e.g., Allium cepa (onion), Allium sativum (garlic) etc.
(ii) Subaerial modifications : Subaerial part of stem grows horizontally on the ground while some part remains underground. Vegetative propagation takes place by means of these. They may be of following kinds.
(a) Runner: It grows prostrate on the surface of soil. It develops at the base of erect shoot called crown. A number of runners arise from one erect shoot which spread in different directions. Each runner has one or more nodes which bear scale leaves and axillary buds, e.g., Cynodon (doob grass).
(b) Stolon: The nodes of horizontally growing underground stem give rise to branches which come out of the soil, e.g., Fragaria (strawberry).
(c) Sucker: Suckers are formed from the node of underground stem. Sucker comes up obliquely in the form of leafy shoot, e.g., Mentha (mint).
(d) Offset: Stem consists of thick and short intemodes. The branches are formed from the main stem and upper portion of each branch bears a group of leaves while the lower portion bears the roots. Each branch is capable of growing as an independent plant after separating from the parent plant, e.g., Eichhornia (water hyacinth), Pistia, etc.
(iii)Aerial modifications : The aerial portion of stem is modified to perform different functions, e.g., climbing, protection, food manufacturing, etc. It may show following types of modifications:
(a) Twinners : The stem is long, flexible and sensitive which can coil around an upright support like a rope, e.g., Ipomoea, Convolvulus.
(b) Climbers : The stem is weak and flexible but is unable to coil around an upright support by itself. It requires the help of clasping or clinging structures. Accordingly, climbers are of four types : root climbers, e.g., Betel tendril climber, e.g., Passiflora scramblers, e.g., Bougainvillea and lianas, e.g., Bauhinia.
(c) Phylloclade: The stem performs the function of photosynthesis. The stem modifies into green fleshy leaf-like
structure having distinct nodes and intemodes. Leaves of such plants are reduced into spines in order to prevent loss of water, e.g., Opantia (prickly pear), Euphorbia.
(d) Cladode: It is similar to phylloclade with only one internode, e.g., Asparagus.
(e) Thorn: Stem is modified into stiff, pointed unbranched or branched structures which have lost their growing point and become hard, called as thorns, e.g., Bougainvillea,Pomegranate, Citrus, etc. They perform defensive function.
(f) Tendrils : These are thread like sensitive structures which can coil around a support and help the plant
in climbing, e.g., Cucurbita.
(g) Bulbils: In some plants vegetative buds or floral buds modify into a swollen structure called bulbil. It separates from the parent plant and on approach of favourable condition gives rise to a new plant, i.e., it is an organ of vegetative reproduction, e.g., Agave, Oxalis.

Q9. Take one flower each of the families Fabaceae and Solanaceae and write their semi-technical description. Also draw their floral diagram after studying them.

Answer: Family Fabaceae (e.g., Pisum sativum) Systematic position:
Class – Dicotyledoneae
Subclass- Polypetalae
Series – Calyciflorae
Order – Rosales
Family – Fabaceae
Vegetative characters:
Habit: herb. Root: tap, branched, with root nodules.
Stem: herbaceous, climbing.
Leaves : pinnately compound, leaf base pulvinate, stipulate, venation reticulate.
Floral characters:
Inflorescence: racemose.
Flower : bisexual, zygomorphic, irregular, hermaphrodite, white or pink, complete, hypogynous to perigynous.
Calyx : sepals five, gamosepalous, ascending, imbricate aestivation, campanulate calyx tube.
Corolla : petals five, polypetalous, vexillary aestivation, papilionaceous, consisting of a posterior standard or vexillum two lateral wings or alae, two anterior ones forming a keel.
Androecium : 10 stamens in two bundles (diadelphous) of (9) + 1, anthers dithecous (bilobed), basifixed, introrse.
Gynoecium : ovary superior, monocarpellary, unilocular with many ovules, marginal placentation, style bent and long, stigma simple and-hairy.
Fruit : legume seeds one to many, non- endospermic.
Floral formula : ncert-solutions-for-class-11-biology-morphology-of-flowering-plants-7
ncert-solutions-for-class-11-biology-morphology-of-flowering-plants-8
Family Solanaceae (e.g., Solanum nigrum) Systematic position:
Class Subclass Series Order Family
Vegetative characters:
Habit: herbs Stem : herbaceous, aerial, erect, cylindrical, branched.
Leaves: alternate, simple, exstipulate, venation reticulate.
Floral characters:
Inflorescence: cymose.
Flower : ebracteate, ebracteolate, bisexual, actinomorphic, white, hypogynous.
Calyx : sepals five, gamosepalous, persistent, valvate aestivation.
Corolla : petals five, gamopetalous, valvate. aestivation.
Androecium : stamens five, epipetalous, polyandrous, anthers large, bithecous and basifixed.
Gynoecium : bicarpellary, syncarpous,
ovary, obliquely placed carpels in the flower, bilocular, axile placentation, placenta swollen with many ovules.
Fruits : berry with persistent calyx.
Floral formula :ncert-solutions-for-class-11-biology-morphology-of-flowering-plants-9
ncert-solutions-for-class-11-biology-morphology-of-flowering-plants-10

Q10. Describe the various types of placentations found in flowering plants.

Answer: Placenta is a parenchymatous cushion present inside the ovary where ovules are borne. The number, position, arrangement or distribution of placentae inside an ovary is called placentation. The placentation are of different types namely, marginal, axile, parietal, basal and free central.
(i)Marginal placentation : The placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, e.g., pea.
(ii)Axile placentation : When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is said to be axile, e.g., china rose, tomato and lemon.
(iii)Parietal placentation : The ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one-chambered but it becomes two-chambered due to the formation of the false septum, e.g., mustard and Argemone.
(iv)Free central placentation : When the ovules are borne on central axis and septa are absent, as in Dianthus and primrose the placentation is called free central.
(v)Basal placentation: The placenta develops at the base of ovary and a single ovule is attached to it, as in sunflower, marigold.

Q11. What is a flower? Describe the parts of a typical angiosperm flower.

Answer: Flower is the reproductive unit in the angiosperms. It is meant for sexual reproduction. A typical flower has four different kinds of whorls arranged successively on the swollen end of the stalk or pedicel, called thalamus or receptacle. These are calyx, corolla, androecium and gynoecium.
Calyx and corolla are accessory organs, while androecium and gynoecium are reproductive organs. In some flowers like lily, the calyx and corolla are not distinct and are termed as perianth. Some flowers have both androecium and gynoecium and are termed hermaphrodite flowers while some flowers have only one of these two whorls.
Calyx : The calyx is the outermost whorl of the flower and its units are called sepals. Generally, sepals are green, leaf like and protect the flower in the bud stage. The calyx may be gamosepalous (sepals united) or polysepalous (sepals free).
Corolla : Corolla is composed of petals. Petals • are usually brightly coloured to attract insects for pollination. Like calyx, corolla may also be free (polypetalous) or united (gamopetalous). The shape and colour of corolla vary greatly in plants. Corolla may be tubular, bell-shaped, funnel-shaped or wheel-shaped.
Androecium : Androecium is the male reproductive part of the flower. It is composed of stamens. Each stamen which represents the male reproductive organ consists of a stalk or a filament and an anther. Each anther is usually bilobed and each lobe has two chambers, the pollen-sacs. The pollen grains are produced in pollen-sacs. A sterile stamen is called staminode.
Gynoecium : Gynoecium is the female reproductive part of the flower and is made up of one or more carpels. A carpel consists of three parts namely stigma, style and ovary. Ovary is the enlarged basal part, on which lies the elongated tube, the style. The style connects the ovary to the stigma. The stigma is usually at the tip of the style and is’ the receptive surface for pollen grains. Each ovary bears one or more ovules attached to a flattened, cushion-like placenta. When more than one carpel is present, they may be free (as in lotus and rose) and are called apocarpous. They are termed syncarpous when carpels are fused, as in mustard and tomato. After fertilisation, the ovules develop into seeds and the ovary matures into a fruit.

Q12. How do the various leaf modifications help plants?

Answer: Leaves perform various functions besides photosynthesis and thus they are modified into different forms such as –
(i)Leaf tendrils: The different parts of a leaf are modified into tendrils which help the plant in climbing up. Parts of leaf modified into tendrils include stipules e.g., Smiiax petiole e.g., Clematis leaf apex e.g., Gloriosa leaflets e.g., Pisum whole leaf e.g., Lathyrus.
(ii)Leaf spines: Either for the protection of plant or to lessen the rate of transpiration in xerophytic plants, the leaves modify into sharp, pointed spines. Parts of leaf modified into leaf spines include stipules e.g., Zizyphus leaf margins e.g., Argemone leaf apex e.g.r Yucca entire leaf e.g., Berberis.
(iii)Phyllode: Petioles modify into leaf¬like green, photosynthesising structure e.g., Parkinsonia, Acacia auriculiformis.
(iv)Scale or protective leaves : The leaves modify into hard scaly leaves which protect the vegetative bud by covering them, e.g., Ficus, Artocarpus, Casuarina, etc.
(v) Leaf hooks : They help in climbing e.g., Bignonia.
(vi)Leaf roots : A leaf transforms into roots for balancing on water e.g., Salvinia.
(vii)Leaf pitchers : Leaf is modified into pitcher e.g., Nepenthes (insectivorous), Dischidia (non-insectivorous).
(viii)Leaf bladder: The leaves modify to form bladder like structure which trap insects and then it is closed by a valve present on the mouth of bladder e.g., Utricularia (bladderwort).
(ix) Leaf tentacles: The leaf of sundew plant, Drosera bear minute hairs which have shinning, sticky substance at their tips (tentacles). When any insect sits on the leaf, it is covered by these hairs.

Q13. Define the term inflorescence. Explain the basis for the different types of inflorescence in flowering plants.

Answer: The arrangement of flowers on the floral axis is termed as inflorescence. A flower is a modified shoot wherein internodes do not elongate and the axis gets condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves. When a shoot tip transforms into a flower, it is always solitary. Depending on whether the apex gets converted into a flower or continues to grow, two major types of inflorescence are defined – racemose and cymose. In racemose type of inflorescence the main axis continues to grow, the flowers are borne laterally in an acropetal succession. In cymose type of inflorescence the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipeta! order.


Morphology of Flowering Plants Questions

A NOVETNLETS (a) / (Unicostate or pinnate - This type of venation is having only one principal vein or midrib that gives Multicostate or palmate - In this type of venation many principal veins arising from the tip of petiole Multicostate Unicostate Zizyphus C Ber RETICULATE VENATION 2. Parallel venation - In this type of venation, all veins run parallel to each other and they donot form network They are of 2 types 290 (a) Unicostate or pinnate : This type of pattern is having only one principal vein, that gives off many lateral veins, which proceed toward the margin of leaf blade in a parallel manner but they donot have ninlop 5) Multicostate or palmate : This type of pattern is having many principal veins ansing from the tip of the petiole and proceeding upwards, eg. Grass cereals Reticulate venation is of 2 types lateral veins which proceed towards margin and apex of lamin eg. Peapar motwork Imara 26 and proceed upward eg. Zizyphus (Ber) Paloste

Morphology of Flowering Plants

Placenta Mesocarp- + endocarp Epicarp Seeds Mesocarp + endocarp True part Placenta T.S. of Cucumber L.S. of Tomato POME. This fruit develops from bi or multicarpellary, syncarpous, inferior ovary, The rind and the fruit and seeds are present in it. Eg, Apple, Pear, These are false fruits Fleshy swollen thalamus sponge are made up of thalamus. The main part of the ovary is like to cartilage. It remains inside Fleshy thalamus Seeds L.S. of Apple of these fruits is edible part. Fleshy thalamus Placenta Mesocarp Seeds endocarp Epicarp Mesocarp + endocarp Seeds Seeds True part of fruit Placenta L.S. of Tomato L.S. of Apple T.S. of Cucumber

Morphology of Flowering Plants

EXERCISES 1. What is meant by modification of root? What type of modification of root is found in the: (a) Banyan tree (b) Turnip (c) Mangrove trees 2. Justify the following statements on the basis of external features: (i) Underground parts of a plant are not always roots. (ii) Flower is a modified shoot. minnately compound leaf different from a palmately compound leaf?

Morphology of Flowering Plants

WILUN wyle yene I. The plasma membrane of the red blood cells has sugar polymers that protrude from its surface and the kind of sugar is controlled by the gene. The gene (1) has three alleles IA, IB and i/º Despite the presence of three alleles of the same gene in a population, an individual (2n) can have only two alleles. Therefore, multiple alleles can be detected only in a population. Since there are three different alleles, therefore six different genotypes are possible character (AJA AIO. BIB BIO.

Morphology of Flowering Plants

117. Verticillaster inflorescence occurs in - (1) Solanaceae (2) Cruciferae (3) Fabaceae (4) Labiatae letely

Morphology of Flowering Plants

01 Anthophore is found in which plant? (1) Capparis (2) Passiflora (3) Dianthus (4) Cleome

Morphology of Flowering Plants

1 117. Verticillaster inflorescence occurs in - (1) Solanaceae (2) Cruciferae (3) Fabaceae (4) Labiatae is completely

Morphology of Flowering Plants

n 2n 35. Which of the following statements is not correct? (a) Pollen grains are released from anthers at 2-celled stage (b) Sporogenous cell directly behaves as the megaspore mother cell (c) Megaspore divides twice to form an eight nucleate embryo sac (d) Egg and synergids always lie near the micropylar end of ovule.

Morphology of Flowering Plants

tious roots 45. Which of the following is an incorrect pair? (a) Phylloclade Opuntia (b) Cladode Ruscus (c) Phyllode Asparagus Grapevine Fowld) Stem tendrils 46 Parkinsoninis Cod

Morphology of Flowering Plants

of ovary? Apple, China Rose, Mustard, Sunflower, Cucumber, Guava, Brinjal, Pea (1) TWO (2) Three (3) Four (4) One shape any of the given below plants have flask Ons of Aakao ped thalamus with internal wall fused with the

Morphology of Flowering Plants

5. Which most often Nimits the primary productivity of the ecosystem? (a) Solar radiation (b) Oxygen (c) Consumers (Oy Nitrogen om

Morphology of Flowering Plants

29. Leaves are lateral, generally flattened structure born on nodes. They originate from . . and arranged in manner .. (1) Apical meristem, Acropetal (2) Lateral meristem, Acropetal (3) Apical meristem, Basipetal (4) Lateral meristem, Basipetal


Xerophytic Adaptations of Plants (Ecological Adaptations of Desert Plants)

Ø Xerophytes (xerophytic plants) are plants growing in dry habitats (xeric conditions) where the availability of water is very less.

Ø Xeric habitat: places where water is NOT present in adequate quantity.

Ø Xerophytes are the characteristic plants of deserts or semi-deserts areas.

Ø Xerophytes can also grow in mesophytic conditions.

Ø Xerophytes can tolerate:

Ø Three types of xeric habitats occurs on the earth:

(1). Physically dry habitat: the water retaining capacity of the soil very low and climate is dry (Example: a desert).

(2). Physiologically dry: water is present in excess, but not in the absorbable conditions or the plants cannot absorb it (Example: high salt water, high acidic water and high cold water, water as snow).

(3). Physically and physiologically dry: water present as mist, plants cannot absorb water from the atmosphere directly. (Example: mountain slopes)

Examples of Xerophytes:

(1). Ephemeral Xerophytes: – Short lived xerophytes

Examples: Tribulus terrestris, Trianthema monogyna, Carthamus oxyacantha

(2). Succulent Xerophytes:plants with fleshy and succulent parts, two types:

(a). Succulents with fleshy stem: Opuntia, Echinocactus, Euphorbia royleana

(b). Succulents with fleshy leaves: They are also called as Malacophyllous xerophytes: Example: Aloe, Agave, Peperomia, Haworthia, Bryophyllum, Kalanchoe

(3). Non-succulent xerophytes: Nerium, Cassuarina, Pinus, Calotropis, Ephedra, Equisetum

Adaptations strategies of xerophytes:

o To absorb as much of water as they can get from the surroundings.

o To retain water in their organ for very long time.

o To reduce the water loss by transpiration to minimum.

o To prevent high consumption of water.

Classification of Xerophytes:

Ø Xerophytes are classified on the basis of their drought resisting power.

(1). Drought escaping plants

(2). Drought enduring plants

(3). Drought resistant plants

(1). Drought Escaping Plants:

Ø They are short lived plants (ephemerals) and they complete their life cycle within few weeks.

Ø They survive in the critical dry periods as seeds or propagules.

Ø They have hard and resistant fruit walls and seed coats for protecting the embryo from extreme dry conditions.

Ø These plants germinate suddenly in the favourable conditions.

Ø They are usually short sized plants in which the flowering and fruiting occur before the next unfavourable season.

Ø Example: Astragalus, Artemesia, Tribulus and most of the grasses.

(2). Drought Enduring Plants:

Ø They are small sized plants that have the capacity to endure or tolerate drought conditions.

Ø These plants usually do not show any xerophytic adaptations.

Ø Most of the individuals in the population will die in the unfavourable season the surviving ones contribute the next generation.

(3). Drought Resistant Plants

Ø They are the true xerophytic plants that can resist the drought conditions.

Ø They develop adaptations to resist the extreme temperature and drought.

Ø On the basis of water storing capacity, xerophytes are classified into two groups:

(1). Succulent xerophytes: they can store water in their plant body.

(2). Non-succulent xerophytes: also called true xerophytes.

Xeromorphic vs Xeroplastic Characters

Plants show TWO types of xerophytic characters (adaptations), they are:

(1). Xeromorphic characters:

Ø Xeromorphic characters are fixed xerophytic characters.

Ø These characters appear in the xerophytes irrespective of the environmental conditions.

Ø Example: Sunken stomata in Cycas Some cactoid Euphorbias.

(2). Xeroplastic characters:

Ø Xeroplastic characters are induced by droughts conditions in the plants.

Ø These characters only appear in plants when they are challenged by xeric conditions.

Ø These characters are not genetically fixed and thus they are not inherited to the next generation.

Xerophytic Adaptations of Plants

Ø Xerophytic characters shown by plants can be grouped into the following THREE categories:

(1). Morphological adaptations: external adaptations

(2). Anatomical adaptations: internal adaptations

(2). Physiological and Reproductive adaptations

Morphological Adaptations of Xerophytes:

(a). Roots of xerophytes

Ø Root system is well developed in true xerophytes.

Ø They are adapted to reach the area where water is available and to absorb water as much as possible”.

Ø Roots will be profusely branched and more elaborate than their stem.

Ø Most of the roots in xerophytes are perennial and they survive for many years.

Ø Roots grow deep into the soil and they can reach a very high depth in the soil.

Ø Root surface is provided with dense root hairs for water and mineral absorption.

(b). Stem of xerophytes

Ø Stem woody and hard in some xerophytic plants.

Ø Stem usually green and photosynthetic.

Ø Stem is covered with thick cuticle, wax and silica (Example: Equisetum).

Ø In many plants, the stem is covered with dense hairs (Example: Calotropis).

Ø Stem modified into thorns in Ulex.

Ø Succulent and bulbous xerophytes can store water in their stem. Example: Cactus and some species of Euphorbia.

Ø Stem may be modified into phylloclades, cladophylls or cladodes.

Ø Phylloclades: Stem modified into flattened leaf-like organs (Muehlenbeckia).

Ø Cladode: Many axillary branches become modified into small needle like green structures which look exactly like leaves (Asparagus).

Ø Cladophyll: branches developed in the axil of scale leaves, become metamorphosed to leaf-like structures (Ruscus).

(c). Leaves of xerophytes

Ø Leaves usually absent in xerophytes.

Ø If leaves are present, usually they are caducous (fall off easily).

Ø Most of the cases the leaves are modified into spines or scales (Casuarina).

Ø Leaf may modify into phyllode in some plants.

Ø Phyllode: leaf petiole or rachis modified (flattened) into leaf like organ Example: Acacia.

Anatomical Adaptations of Xerophytes:

(a). Roots

Ø Root hairs are well developed in xerophytes.

Ø Roots with well-developed root cap.

Ø In Asparagus, the roots become fleshy and store plenty of water.

Ø In Calotropis, root cells are with very rigid cell wall.

Ø In succulent xerophytes, the stem possesses water storing regions.

Ø Epidermis is well developed and with thick walled compactly packed cells.

Ø Cuticle is very thick and well developed over the epidermis.

Ø Hypodermis is several layered often hypodermis will be sclerenchymatous (Casuarina).

Ø Stomata are present on the stem for gaseous exchange and transpiration.

Ø Stomata are sunken type and usually situated in pits provided with hairs (Casuarina).

Ø Vascular tissue is well developed with prominent xylem and phloem components.

Ø In most of the xerophytes, the bark will be well developed and thick.

Ø Many oil and resin canals are present in bark.

Ø Most of the cases, the stem will be photosynthetic and contains chlorenchymatous cells in the outer cortex.

Ø In the stem of Casuarina, the chlorenchymatous cells are radially elongated and palisade like tissue in appearance.

Ø Epidermis of the leaf is thick and may be multilayered.

Ø Thick cuticle present over the outer tangential wall of the epidermal cells.

Ø In some plants, the epidermal cells can store water.

Ø In some monocots, some epidermal cells are larger than rest of the cells.

Ø These cells are called bulliform cells.

Ø Bulliform cells are motor cells and they assist in leaf rolling to reduce transpiration.

Ø Hypodermis usually present.

Ø In Pinus, the hypodermis sclerenchymatous.

Ø Mesophyll is well developed in xerophytic leaves.

Ø Many layered palisade tissue present.

Ø Spongy tissue is less developed in xerophytes with less intercellular spaces.

Ø Leaves of Aloe have water storing region in the mesophyll.

Ø Stomata are reduced in numbers and are situated only on the lower sides of the leaves (hypostomatic leaves).

Ø Stomata are sunken type and usually situated in pits with hairs (Nerium).

Ø Vascular tissue is well developed with plenty of xylem elements.

Ø Mechanical tissue well developed in the leaves of xerophytes.

Ø Transfusion tissue, if present, will be well developed for the lateral conduction.

(3). Physiological adaptations of xerophytes:

Ø Structural or morphological adaptations of xerophytes are well suited to survive in drought conditions.

Ø Xerophytic plants are reported to contain pentosan polysaccharides which are reported to offer resistance against drought conditions.

Ø Many xerophytes show CAM (Crassulacean Acid Metabolism) cycle.

Ø In CAM plants, the stomata will be closed at day time.

Ø Stomata open during the night and they absorb enough carbon dioxide for the photosynthesis.

Ø Absorbed carbon dioxide is converted into malic acid and store in the vacuoles of the cells.

Ø The malic acid increases the osmotic concentration of cell sap and this enables the closure of stomata in the day time.

Ø Some enzymes such as catalase and peroxidase are more active in xerophytes.

Ø Amylase enzyme in xerophytes is more efficient in the hydrolysis of starch than mesophytes.

Ø Xerophytes can regulate the rate of transpiration.

Ø They ensure the reduced rate of transpirational loss of water by thick cuticle, distribution of stomata in the lower side of the leaf, sunken type of stomata, and positioning of stomata in pits with many hairs.

Ø Xerophytes possess high osmotic concentration of cell sap.

Ø Thus cells have high osmotic pressure.

Ø High osmotic pressure increases the turgidity of the cells.

Ø Turgidity exerts tension force (turgor pressure) on cell wall.

Ø Due to this high turgor pressure, the wilting of cells is prevented by the extreme heat.

Ø High osmotic concentration also ensures the rapid and effective absorption of water.

Ø Tissue of succulents possesses mucilage to hold large amount of water.

Ø Loss of high proportion of body mass with rapid recovery when water is available.

Ø Produce brightly coloured, large and showy flowers for attracting pollination agents.

Ø Cactoid plants produce large amounts of minute seeds.

Ø Seeds are with thick seed coat for protection.

Ø Seed surface also possesses mucilage substances to absorb and hold water when it is available.

Ø Some plants quickly complete their life cycle before the unfavourable conditions.

Ø Efficient pollination mechanism by moths, bats and birds.

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NCERT Solutions For Class 11 Biology Morphology of Flowering Plants

Topics and Subtopics in NCERT Solutions for Class 11 Biology Chapter 5 Morphology of Flowering Plants:

Section Name Topic Name
5 Morphology of Flowering Plants
5.1 The Root
5.2 The Stem
5.3 The Leaf
5.4 The Inflorescence
5.5 The Flower
5.6 The Fruit
5.7 The Seed
5.8 Semi-technical Description of a Typical Flowering Plant
5.9 Description of Some Important Families
5.10 Summary

NCRT TEXTBOOK QUESTIONS SOLVED

1.What is meant by modification of root? What type of modification of root is found in the:
(a) Banyan tree
(b) Turnip
(c) Mangrove trees
Soln. Roots of some plants change their shape and structure and become modified to perform certain functions other than absorption and conduction of water and minerals. It is called modification of roots. Roots are modified for support, storage of food and respiration, etc.
(a) Root modification in banyan tree : In banyan tree, the root modifies to form prop roots. Prop roots arise from branches and enter the soil. Thus, they provide mechanical support to densely branched, huge trees.
(b) Root modification in turnip : The
modification of root found in turnip is napiform for food storage. The upper portion of these fleshy roots is inflated or swollen which tapers towards the lower end.
(c) Root modification in mangrove trees : In mangrove plants, i.e., plants growing in saline marshes, the branches of tap root come out of the ground and grow vertically upwards showing negative geotropism. These roots are called pneumatophores. They help to get oxygen for respiration.

2.Justify the following statements on the basis of external features:
(i) Underground parts of a plant are not always roots.
(ii) Flower is a modified shoot.
Soln. (i) Underground parts of plant are not always roots because sometimes the stem also becomes underground and gets modified into various forms to perform different functions of storage, vegetative propagation, perennation, etc. Underground modifications of stems are tuber, rhizome, corm and bulb. The underground stems can be distinguished from roots externally by the presence of nodes and internodes, axillary buds, scale leaves etc. and by absence of root cap and root hairs.
(ii) Flower is the reproductive part of the angiospermic plant and it is defined as the modified shoot because (a) like shoot, flower develops from an axillary or rarely terminal bud. (b) flowers may get modified into fleshy buds or bulbils, (c) A transition from foliage leaves to floral leaves is found in Paeonia. (d) Nymphaea shows transition from sepals to petals and petals to stamens, (e) In Passiflora and Cleome long intemodes occur below gynoecium and stamens.

More Resources for CBSE Class 11

3.How is a pinnately compound leaf different from a palmately compound leaf?
Soln. The compound leaves may be of two types, pinnately compound leaf and palmately compound leaf. In pinnately compound leaf, a number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf as in neem. Pinnately compound leaf may be of different types as unipinnate, bipinna te, tripinna te and decompound. In palmately compound leaf, the leaflets are attached at a common point, i.e., at the tip of petiole, as in silk cotton. Palmately compound leaf may be of different types as unifoliate, bifoliate, trifoliate, quadrifoliate and multifoliate.

4.Explain with suitable examples the different types of phyllotaxy.
Soln. Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. It is usually of three types – alternate, opposite and whorled. In alternate type of phyllotaxy, a single leaf arises at each node in alternate manner, as in china rose, mustard and sunflower plants. In opposite type, a pair of leaves arises at each node and lie opposite to each other as in Calotropis and guava plants.
If more than two leaves arise at a node and form a whorl it is called whorled phyllotaxy as in Alstonia.

5.Define the following terms:
(a) aestivation (b) placentation
(c) actinomorphic (d) zygomorphic
(e) superior ovary (f) perigynous flower (g) epipetalous stamen.
Soln. (a) Aestivation : The mode of arrange¬ment of accessory floral organs (sepals and petals) in relation to one another in floral bud is known as aestivation. The main type of aestivation are valvate, twisted, imbricate, and vexillary.
(b) Placentation : The arrangement of ovules within the ovary is known as placentation. The placentation are of different types namely, marginal, axile, parietal, basal, and free central.
(c) Actinomorphic : When flower can be divided into equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic, e.g., mustard, Datura etc.
(d) Zygomorphic : When a flower can be divided into two similar halves only in one particular vertical plane, it is said to be zygomorphic, e.g., pea, gulmohar, bean, Cassia.
(e) Superior ovary : In hypogynous flower, the gynoecium occupies the highest position while the other parts are situated below it. The ovary in such flowers is said to be superior, e.g., mustard, brinjal.
(f) Perigynous flower: If gynoecium is situated in the centre and other parts of the flower are
located on the rim of the thalamus almost at the same level, it is called perigynous. Here ovary is half superior, e.g., peach, plum.
(g) Epipetalous stamen : When stamens are attached to the petals, they are called epipetalous stamens e.g., brinjal.

6.Differentiate between
(a) Racemose and cymose inflorescence
(b) Fibrous root and adventitious root
(c) Apocarpous and syncarpous ovary
Soln.
(a) Differences between racemose and cymose inflorescence are as follows:

(b) Differences between fibrous and adventitious roots are as follows :


(c) Differences between apocarpous and syncarpous ovary are as follows :

7.Draw the labelled diagram of the following:
(i) Gram seed (ii) V. S. of maize seed.
Soln.
(i) Gram seed.

(ii) V.S. of maize seed.

8.Describe modifications of stem with suitable examples.
Soln. Stems are modified to perform different functions. Underground stems of some plants are modified to store food in them. They also act as organs of perennation to tide over conditions unfavourable for growth. Different modifications of stem are :
(i) Underground modifications
(ii)Sub-aerial modifications
(iii)Aerial modifications
(i)Underground modifications of stem are discussed as follows:
(a)Tuber: It is the branch of main stem which accumulates or stores food in it and swells up, e.g., Solarium tuberosum (potato).
(b) Rhizome: It is a branched, prostrate horizontally growing stem having nodes and internodes. On the nodes sessile scale leaves are formed, e.g., Carina, Zingiber officinale (ginger), Curcuma domestica (turmeric) etc.
(c) Corm: This is a spherical,
branched, vertically growing thick underground stem with more diameter than length, e.g., Crocus sativus (saffron), Gladiolus, Colocasia esculenta (arvi) etc.
(d) Bulb: In bulb the stem is highly reduced and can be seen only as a disc-like structure bearing numerous fleshy scaly leaves, e.g., Allium cepa (onion), Allium sativum (garlic) etc.
(ii) Subaerial modifications : Subaerial part of stem grows horizontally on the ground while some part remains underground. Vegetative propagation takes place by means of these. They may be of following kinds.
(a) Runner: It grows prostrate on the surface of soil. It develops at the base of erect shoot called crown. A number of runners arise from one erect shoot which spread in different directions. Each runner has one or more nodes which bear scale leaves and axillary buds, e.g., Cynodon (doob grass).
(b) Stolon: The nodes of horizontally growing underground stem give rise to branches which come out of the soil, e.g., Fragaria (strawberry).
(c) Sucker: Suckers are formed from the node of underground stem. Sucker comes up obliquely in the form of leafy shoot, e.g., Mentha (mint).
(d) Offset: Stem consists of thick and short intemodes. The branches are formed from the main stem and upper portion of each branch bears a group of leaves while the lower portion bears the roots. Each branch is capable of growing as an independent plant after separating from the parent plant, e.g., Eichhornia (water hyacinth), Pistia, etc.
(iii)Aerial modifications : The aerial portion of stem is modified to perform different functions, e.g., climbing, protection, food manufacturing, etc. It may show following types of modifications:
(a) Twinners : The stem is long, flexible and sensitive which can coil around an upright support like a rope, e.g., Ipomoea, Convolvulus.
(b) Climbers : The stem is weak and flexible but is unable to coil around an upright support by itself. It requires the help of clasping or clinging structures. Accordingly, climbers are of four types : root climbers, e.g., Betel tendril climber, e.g., Passiflora scramblers, e.g., Bougainvillea and lianas, e.g., Bauhinia.
(c) Phylloclade: The stem performs the function of photosynthesis. The stem modifies into green fleshy leaf-like
structure having distinct nodes and intemodes. Leaves of such plants are reduced into spines in order to prevent loss of water, e.g., Opantia (prickly pear), Euphorbia.
(d) Cladode: It is similar to phylloclade with only one internode, e.g., Asparagus.
(e) Thorn: Stem is modified into stiff, pointed unbranched or branched structures which have lost their growing point and become hard, called as thorns, e.g., Bougainvillea,Pomegranate, Citrus, etc. They perform defensive function.
(f) Tendrils : These are thread like sensitive structures which can coil around a support and help the plant
in climbing, e.g., Cucurbita.
(g) Bulbils: In some plants vegetative buds or floral buds modify into a swollen structure called bulbil. It separates from the parent plant and on approach of favourable condition gives rise to a new plant, i.e., it is an organ of vegetative reproduction, e.g., Agave, Oxalis.

9.Take one flower each of the families Fabaceae and Solanaceae and write their semi-technical description. Also draw their floral diagram after studying them.
Soln. Family Fabaceae (e.g., Pisum sativum) Systematic position:
Class – Dicotyledoneae
Subclass- Polypetalae
Series – Calyciflorae
Order – Rosales
Family – Fabaceae
Vegetative characters:
Habit: herb. Root: tap, branched, with root nodules.
Stem: herbaceous, climbing.
Leaves : pinnately compound, leaf base pulvinate, stipulate, venation reticulate.
Floral characters:
Inflorescence: racemose.
Flower : bisexual, zygomorphic, irregular, hermaphrodite, white or pink, complete, hypogynous to perigynous.
Calyx : sepals five, gamosepalous, ascending, imbricate aestivation, campanulate calyx tube.
Corolla : petals five, polypetalous, vexillary aestivation, papilionaceous, consisting of a posterior standard or vexillum two lateral wings or alae, two anterior ones forming a keel.
Androecium : 10 stamens in two bundles (diadelphous) of (9) + 1, anthers dithecous (bilobed), basifixed, introrse.
Gynoecium : ovary superior, monocarpellary, unilocular with many ovules, marginal placentation, style bent and long, stigma simple and-hairy.
Fruit : legume seeds one to many, non- endospermic.
Floral formula :

Family Solanaceae (e.g., Solanum nigrum) Systematic position:
Class Subclass Series Order Family
Vegetative characters:
Habit: herbs Stem : herbaceous, aerial, erect, cylindrical, branched.
Leaves: alternate, simple, exstipulate, venation reticulate.
Floral characters:
Inflorescence: cymose.
Flower : ebracteate, ebracteolate, bisexual, actinomorphic, white, hypogynous.
Calyx : sepals five, gamosepalous, persistent, valvate aestivation.
Corolla : petals five, gamopetalous, valvate. aestivation.
Androecium : stamens five, epipetalous, polyandrous, anthers large, bithecous and basifixed.
Gynoecium : bicarpellary, syncarpous,
ovary, obliquely placed carpels in the flower, bilocular, axile placentation, placenta swollen with many ovules.
Fruits : berry with persistent calyx.
Floral formula :

10.Describe the various types of placentations found in flowering plants.
Soln. Placenta is a parenchymatous cushion present inside the ovary where ovules are borne. The number, position, arrangement or distribution of placentae inside an ovary is called placentation. The placentation are of different types namely, marginal, axile, parietal, basal and free central.
(i)Marginal placentation : The placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, e.g., pea.
(ii)Axile placentation : When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is said to be axile, e.g., china rose, tomato and lemon.
(iii)Parietal placentation : The ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one-chambered but it becomes two-chambered due to the formation of the false septum, e.g., mustard and Argemone.
(iv)Free central placentation : When the ovules are borne on central axis and septa are absent, as in Dianthus and primrose the placentation is called free central.
(v)Basal placentation: The placenta develops at the base of ovary and a single ovule is attached to it, as in sunflower, marigold.

11.What is a flower? Describe the parts of a typical angiosperm flower.
Soln. Flower is the reproductive unit in the angiosperms. It is meant for sexual reproduction. A typical flower has four different kinds of whorls arranged successively on the swollen end of the stalk or pedicel, called thalamus or receptacle. These are calyx, corolla, androecium and gynoecium.
Calyx and corolla are accessory organs, while androecium and gynoecium are reproductive organs. In some flowers like lily, the calyx and corolla are not distinct and are termed as perianth. Some flowers have both androecium and gynoecium and are termed hermaphrodite flowers while some flowers have only one of these two whorls.
Calyx : The calyx is the outermost whorl of the flower and its units are called sepals. Generally, sepals are green, leaf like and protect the flower in the bud stage. The calyx may be gamosepalous (sepals united) or polysepalous (sepals free).
Corolla : Corolla is composed of petals. Petals • are usually brightly coloured to attract insects for pollination. Like calyx, corolla may also be free (polypetalous) or united (gamopetalous). The shape and colour of corolla vary greatly in plants. Corolla may be tubular, bell-shaped, funnel-shaped or wheel-shaped.
Androecium : Androecium is the male reproductive part of the flower. It is composed of stamens. Each stamen which represents the male reproductive organ consists of a stalk or a filament and an anther. Each anther is usually bilobed and each lobe has two chambers, the pollen-sacs. The pollen grains are produced in pollen-sacs. A sterile stamen is called staminode.
Gynoecium : Gynoecium is the female reproductive part of the flower and is made up of one or more carpels. A carpel consists of three parts namely stigma, style and ovary. Ovary is the enlarged basal part, on which lies the elongated tube, the style. The style connects the ovary to the stigma. The stigma is usually at the tip of the style and is’ the receptive surface for pollen grains. Each ovary bears one or more ovules attached to a flattened, cushion-like placenta. When more than one carpel is present, they may be free (as in lotus and rose) and are called apocarpous. They are termed syncarpous when carpels are fused, as in mustard and tomato. After fertilisation, the ovules develop into seeds and the ovary matures into a fruit.

12. How do the various leaf modifications help plants?
Soln. Leaves perform various functions besides photosynthesis and thus they are modified into different forms such as –
(i)Leaf tendrils: The different parts of a leaf are modified into tendrils which help the plant in climbing up. Parts of leaf modified into tendrils include stipules e.g., Smiiax petiole e.g., Clematis leaf apex e.g., Gloriosa leaflets e.g., Pisum whole leaf e.g., Lathyrus.
(ii)Leaf spines: Either for the protection of plant or to lessen the rate of transpiration in xerophytic plants, the leaves modify into sharp, pointed spines. Parts of leaf modified into leaf spines include stipules e.g., Zizyphus leaf margins e.g., Argemone leaf apex e.g.r Yucca entire leaf e.g., Berberis.
(iii)Phyllode: Petioles modify into leaf¬like green, photosynthesising structure e.g., Parkinsonia, Acacia auriculiformis.
(iv)Scale or protective leaves : The leaves modify into hard scaly leaves which protect the vegetative bud by covering them, e.g., Ficus, Artocarpus, Casuarina, etc.
(v) Leaf hooks : They help in climbing e.g., Bignonia.
(vi)Leaf roots : A leaf transforms into roots for balancing on water e.g., Salvinia.
(vii)Leaf pitchers : Leaf is modified into pitcher e.g., Nepenthes (insectivorous), Dischidia (non-insectivorous).
(viii)Leaf bladder: The leaves modify to form bladder like structure which trap insects and then it is closed by a valve present on the mouth of bladder e.g., Utricularia (bladderwort).
(ix) Leaf tentacles: The leaf of sundew plant, Drosera bear minute hairs which have shinning, sticky substance at their tips (tentacles). When any insect sits on the leaf, it is covered by these hairs.

13. Define the term inflorescence. Explain the basis for the different types of inflorescence in flowering plants.
Soln. The arrangement of flowers on the floral axis is termed as inflorescence. A flower is a modified shoot wherein internodes do not elongate and the axis gets condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves. When a shoot tip transforms into a flower, it is always solitary. Depending on whether the apex gets converted into a flower or continues to grow, two major types of inflorescence are defined – racemose and cymose. In racemose type of inflorescence the main axis continues to grow, the flowers are borne laterally in acropetal succession. In cymose type of inflorescence the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipeta! order.

14. Write the floral formula of an actinomorphic, bisexual, hypogynous flower with five united sepals, five free petals, five free stamens and two united carples with superior ovary and axile placentation.
Soln. The floral formula for actinomorphic, bisexual, hypogynous flower with five united sepals, five free petals, five free stamens and two united carples with superior ovary and
axile placentation is:


NCERT solutions for class 11 biology chapter 5 morphology of flowering plants: Solved Exercise Questions

Roots are the underground water and mineral absorbing parts of the plants. Apart from the function of water and mineral absorption, roots of some plants often modify to perform various other functions such as storage, nitrogen fixation, aeration and support etc. These are called root modifications.

The modification of root found in

(a) Banyan tree- In banyan tree roots modify to provide support to the tree. The banyan tree possesses pillar-like adventitious roots that arise from the aerial part of the stem. These roots grow towards the ground and provide support to the tree. Such roots are called prop roots.

(b) Turnip- The roots of turnip are called napiform roots and they help in the storage of food.

(c) Mangrove tree- These possess roots that modify for the absorption of oxygen by growing vertically upwards from the soil. These types of roots are called pneumatophores.

Roots of a plant are generally underground while the stem is present above the ground. However, it is not necessary that root is the only part of the plant to be found underground. In some specific conditions, stems are also found to be present in underground regions. For example, The stems in ginger and banana are underground and swollen due to the storage of food. They are called rhizomes. Similarly, the corm is an underground stem in Colocasia. Similarly, in peanuts, the flower after fertilization gets pushed inside the soil by growing a flower stalk. Hence, by this information, we can conclude that underground parts of a plant are not always roots.

After a certain period of growth, the apical meristem of a stem gives rise to the floral meristem. While the formation of the floral meristem, the axis of the stem gets condensed, and the internodes lie near each other. Various floral appendages arise from the node. A flower can be said to be a modified shoot because of the presence of nodes and internodes.

Pinnately compound leaf Palmately compound leaf
In a Pinnately compound leaves , a number of leaflets are present on a common axis called rachis. Example- Neem. In Palmately compound leaves , the leaflets are attached at a common point. Example- Silk cotton.

The pattern of arrangement of leaves on the stem or branch is called Phyllotaxy . There are three types of phyllotaxy found in plants.

1. Alternate phyllotaxy- On a branch, a single leaf arises at each node. E.g China rose

2. Opposite phyllotaxy- At one node, two leaves arise, opposite to each other. E.g guava plant

3. Whorled phyllotaxy- More than two leaves arise at a node and form a whorl in whorled phyllotaxy. E.g Alstonia

NCERT solutions for class 11 biology chapter 5 morphology of flowering plants:

Aestivation- The mode of arrangement of sepals or petals in the floral bud with respect to the other members of the same whorl is called aestivation. Aestivation in plants can be valvate, Wisted, imbricate, and vexillary.

Placentation- The arrangement of ovules within the ovary is called placentation. There are five types of placentation found in plants including marginal, basal, parietal, axile, and free central placentation.

Actinomorphic- The flowers which can be divided into two radial halves by any radial plane passing through its centre are called actinomorphic flowers. E.g. chilly and mustard.

Zygomorphic- The flowers which can be divided into two similar halves by a single vertical plane only are known as zygomorphic flowers. E.g. pea and beans.

Superior ovary- When the gynoecium is present at the highest position, while other floral parts are arranged below it, the ovary is said to be a superior ovary. A flower with this arrangement is described as hypogynous. Examples include brinjal and mustard.

Perigynous flower- When the gynoecium is present in the centre while the rest of the floral parts are present at the rim of the thalamus at the same level as gynoecium, the flower is called perigynous flower. E.g. plum and rose.

Epipetalous stamen- The stamen which remains attached to the petals are called epipetalous stamens. E.g brinjal

Racemose inflorescence Cymose inflorescence
The main axis of flower continues to grow and produce flowers laterally in racemose inflorescence The main axis of the flower has limited growth and it terminates into a flower.
Flowers grow in acropetal succession. The younger flowers are present at the tip while older flowers are found at the base. The older flowers are present at the tip whereas the younger flowers are found at the base of the axis.
Fibrous root Adventitious root
The primary root is replaced by a large number of roots at its base of the stem to constitute the Fibrous roots The roots that arise from any part of the plant apart from radicle are called adventitious roots.
The examples of fibrous roots include wheat, rice etc The examples of plants with adventitious roots include grass, banyan tree, maize etc.
Apocarpous ovary syncarpous ovary
In a flower, when more than one free carpels are present, the ovary is called apocarpous ovary In a flower, when more than one carpels are found and they are fused, the ovary is called syncarpous ovary.
Examples of the apocarpous ovary include lotus and rose Examples of the syncarpous ovary include mustard and tomato

NCERT solutions for class 11 biology chapter 5 morphology of flowering plants:

The major types of stem modifications are as follows:

1. Rhizome- It is fleshy, non-green underground stem having distinct nodes and internodes. The nodes bear dry scale leaves with axillary buds. Adventitious roots arise from the lower side. e..g., Alocasia, Dryopteris, Banana, Ginger, turmeric, Canna etc.

2. Bulb- It is an underground pyriform to spherical structure bearing a reduced convex or slightly conical disc-shaped stem and several fleshy scales enclosing a terminal bud. e.g., Lily, onion etc.

3. Corm- It is a condensed form of rhizome growing in the vertical direction. It is more or less spherical with a flat base. Adventitious roots arise either from its base or all over the body. Examples- Colocasia, Amorphophallus.

4. Tuber- Stem tuber is a swollen tip of an underground stem. It possesses a number of small depressions called eyes. These eyes represent nodes. Adventitious roots are usually absent e.g., Potato.

5. Runner- These are special, narrow, green, above ground horizontal or prostrate branches which develop at the bases of erect shoots called crowns. E.g. Centella, Oxalis, doob grass etc.

6. Stolon- These are elongated horizontal runners which can cross over small obstacles. The tip of the stolon generally grows above the level of the ground. E.g. Jasmine, peppermint, wild strawberry etc.

7. Offset- They are one internode long small runners which are found in rosette plants at the ground level. E.g Pistia, Eichhornia etc.

8. Stem- tendrils- These are thread like sensitive structures that coil around a support and help the plant in climbing. E.g. grapevine.

9. Stem thorn- These are hard, stiff and sharp structures which protect the plants. E.g. Citrus, Bougainvillea, Duranta etc.

10. Phylloclade- They are flattened or cylindrical green stems of unlimited growth which have taken over the function of photosynthesis. Formation of phylloclades helps the plants to grow in dry habitats. e.g. Opuntia, Casuarina etc.

11. Cladode- These are the green stem of limited growth which have taken over the function of photosynthesis from the leaves. The true leaves are reduced to scales or spines. E.g. Ruscus.

Placentation refers to the arrangement of ovules within the ovary of a flower. There can be 5 types of placentation in plants. These are as follows:

1. Marginal placentation : The placenta forms a ridge along the ventral suture of the ovary and the ovules develop on two separate rows in marginal placentation e.g. peas.

2. Parietal placentation: When the ovules develop on the inner walls of the ovary, the ovary is said to have parietal placentation.

3. Axile placentation : In axile placentation, the placenta is axial and ovules are attached to it e.g. China rose, lemon, and tomato.

4. Basal placentation : In basal placentation, the placenta develops from its base and a single ovule is found attached to the base. It is found in marigold and sunflower.

5. Free central placentation: The ovules develop on the central axis while the septa are absent in free central placentation. This type of placentation is found in Dianthus and primrose .

Flower is the reproductive part of angiospermic plants for sexual means of reproduction. A typical flower has four whorls arranged on a swollen end of stalk or pedicel called thalamus. They are Calyx, Corolla, Androecium and Gynoecium.

1. Calyx- It is the outermost whorl of a flower. It is made up of units called sepals. It is generally green in colour and protective in function.

2. Corolla- It is the whorl present inner to the corolla. It consists of petals. The petals are brightly coloured to attract the insects.

3. Androecium- It is the whorl present next to the corolla. The androecium mainly consists of stamens which are the male reproductive unit of a flower. A stamen is composed of two parts i.e. anther and filament. The anther is the bilobed structure with a stalk called filament. Inside the anther, pollen grains are formed.

4. Gynoecium- The innermost whorl of a flower is called gynoecium. It consists of pistils. A pistil is composed of three parts stigma, style and ovary. Pistils are the female reproductive units of a flower.

Leaf is a green, lateral and flattened outgrowth which is borne on the node of a stem or its branches is specialized to perform photosynthesis. Apart from photosynthesis, leaves often modify to perform several other functions also. Some of the modifications of leaves in plants that help the plants are as follows:

1. Tendrils- The leaves of the plants may modify into tendrils that help the plants in climbing

2. Spines- These are hard and stiff structures that act as organs of defence. e.g. cactus

3. Phyllode- The leaves of some plants are short-lived and they are soon replaced by flattened, green structures called phyllodes. These arise from the petiole of the leaves and involved in synthesising the food.

4. Pitcher- The leaves of the pitcher plant are modified into pitcher-like structures. These contain digestive juices and help in trapping and digesting insects.

The arrangement of flowers on the floral axis is termed inflorescence. There can be two types of the inflorescence i.e. racemose and cymose on the basis of whether the floral axis continues to grow or end in a flower. In racemose inflorescence, the floral axis continuous to grow and bear flowers whereas in cymose inflorescence the floral axis stopped growing and terminates into a flower.

The floral formula of an actinomorphic, bisexual, hypogynous flower with five united sepals, five free petals, five free stamens and two united carpels with the superior ovary and axile placentation is as follows:

There can be three types of arrangements of floral members in relation to their insertion on the thalamus. These are as follows:

1. Hypogynous – Ovary occupies the highest position while the other parts are situated below the ovary. The ovary in such case is called superior. Eg. Mustard, brinjal and China rose. Flowers with this arrangement are called hypogynous flowers.

2. Perigynous -In this arrangement, the gynoecium is situated at the centre and other parts are on the rim at the same height. Such ovary is called half-inferior and flowers are called perigynous flowers.

3. Epigynous- In this arrangement, the ovary is situated below all the other parts. The ovary, in this case, is said to be inferior while the flower is called epigynous flower.

If you are unable to determine these questions or facing any problem to understand them, then go through the book again and then try to solve all the given questions by yourself and then match it from the CBSE NCERT solutions for class 11 biology chapter 4 animal kingdom, as it will help you to prepare not only for the 12th board exam even also for other competitive exams like NEET.


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