NCERT Class 11 Biology Chapter 5 Notes Morphology Of Flowering Plants- Download PDF Notes

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This chapter explains the outer parts of flowering plants, like roots, stems, leaves, flowers, and fruits. It also covers different types and functions of these parts in simple terms. Students can download the PDF of the Morphology of Flowering Plants Class 11 Notes to study anytime. Going through the whole textbook can take time, so short NCERT Class 11 Biology Notes help revise faster.

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NCERT Class 11 Biology Chapter 5 Notes

Going through the notes is important for improving what students have learned and guiding them easily. For this reason, detailed notes of this chapter are provided below. The Morphology of Flowering Plants Class 11 Notes cover concepts, important diagrams, and frequently asked questions to help students prepare thoroughly. By revising them regularly, you can strengthen their basics and score better in exams. Students have to relate these concepts to real-life plant examples for better retention.

Morphology of Flowering Plants

The plant kingdom consists of a great variety of individuals ranging from simple, minute, microscopic forms to highly developed and complex forms. The flowering plants are a dominant part of Earth’s vegetation and are highly evolved and structurally specialised. With 300,000 known species, flowering plants are the most diverse group of land plants. The body of a flowering plant can be divided into fundamental parts:

(i) an underground root system

(ii) an above-ground shoot system.

These two systems live under very different conditions; the root system grows downward, and the shoot system grows upward.

Root System

The root is non-green, cylindrical and the downward part of the plant. It develops from the radical and is the first structure that comes out when a seed is placed in the soil.

Characteristics of the Root

1. The root is the descending portion of the plant and is usually devoid of chlorophyll.
2. Normally, it does not have any buds, but in some plants like sweet potato, it has buds that help in vegetative propagation.
3. It ends in and is protected by a cap known as a root cap.
4. It is not differentiated into nodes and internodes.
5. It is positively geotropic.

Functions of the root

1. They take up water from the soil.
2. They move mineral salts from the soil water into the plant cells.
3. They are flexible and able to tolerate the strong pulling forces exerted when the wind blows.
4. In some plants, roots form where the plant stores the food it needs over winter.

Parts of a Typical Root

The roots mainly consist of four parts, which are described below:

1. Root cap: The root is covered at the top by a cap or thimble-like structure. Most plants have a simple root cap, but a multiple root cap is found in some plants.
2. Meristematic zone: This is the growing apex of the root that lies within but a little beyond the root cap. The cells of this are thin-walled with dense cytoplasm and large nuclei.
3. Zone of Elongation: This zone is situated just above the meristematic zone. The cells of this zone undergo rapid elongation and enlargement, and they are responsible for the growth of the root in length.
4. Zone of cell maturation: This zone lies above the region of elongation. The cells of this zone undergo maturation and differentiation into various kinds of primary tissues. This produces root hairs that increase the absorbing surface of the root.

Modifications of roots

• Roots are transformed to aid in storage, nitrogen fixation, aeration, and support.
• Carrot tap root, turnip tap root, and sweet potato's adventitious root swell to store food.
• Banyan's prop root and maize, and sugarcane stilt root have supporting roots that emerge from the lower node of the stem.
• Pneumatophores help Rhizophora get oxygen for respiration because it grows in swampy areas.

The Shoot System: The Stem

The shoot is generally above ground, erect, and the ascending axis of the plant body, which develops from the plumule of the embryo. It is differentiated into nodes and internodes and bears leaves, branches, and flowers.

Characteristics of the stem

Some features of the stem are as follows:

1. The stem is the ascending portion of the plant.
2. The young stem is green and carries out photosynthesis.
3. It bears both vegetative and floral buds.
4. It bears mostly multicellular hairs of various kinds, which are scattered over the whole surface.
5. It is positively phototropic.
6. It has distinct nodes and internodes.

Functions of the stem

The stem carries out a variety of functions:

1. It provides support for the main body of the plant.

2. It supports leaves in such positions so that they can capture maximum sunlight.

3. It allows the transport of water, sugars, and other dissolved substances to the various parts of the plant.

4. In some plants, the stem forms where they store food.

Modifications of Stem:

• Stems can be modified to perform a variety of functions. Stems that are underground, like Potato, ginger, turmeric, zaminkand, and Colocasia, have been modified to store food.
• They also serve as organs of perennation, allowing them to survive in unfavourable growth conditions.
• Stem tendrils, which emerge from axillary buds and are slender and spirally coiled, aid in the climbing of plants such as gourds (cucumber, pumpkins, and watermelon) and grapevines.
• Stem’s axillary buds can also be transformed into woody, straight, and pointed thorns.
• Thorns can be found in a variety of plants, including citrus and bougainvillaea. They shield plants from grazing animals. Some arid-zone plants sculpt their stems into flattened (Opuntia) or fleshy cylindrical (Euphorbia) structures. They have chlorophyll and perform photosynthesis.
• Grass and strawberries, for example, spread their underground stems to new niches, and when older parts die, new plants emerge. A slender lateral branch emerges from the base of the main axis in plants such as mint and jasmine, and after growing aerially for a time, arches downwards to touch the ground.
• Aquatic plants such as Pistia and Eichhornia have lateral branches with short internodes, and each node contains a rosette of leaves and a tuft of roots.
• The lateral branches of bananas, pineapples, and Chrysanthemums emerge from the main stem's basal and underground portion, grow horizontally beneath the soil, and then emerge obliquely upward, giving rise to leafy shoots.

The Leaf

The leaf is a flattened, lateral outgrowth of the stem or the branches, developing from a node and having a bud in its axil.

Characteristics of the leaf

The following are distinctive characteristics of leaves:

• They are lateral outgrowths of the stem.

• They arise at the nodes of the stem.

• They are exogenous in origin.

• They bear buds in their axil.

Functions of the leaf

Leaves are green, usually flat structures with a large surface area exposed to the sun. Some important functions of the leaves are as follows:

• Leaves contain chlorophyll, which is involved in the reactions of photosynthesis.

• They supply water and carbon dioxide to the site of photosynthesis.

• They have a transport system to remove the products of photosynthesis so that they can be carried around the plant.

Parts of a leaf

A typical leaf is differentiated into three parts: the leaf base, petiole, and lamina.

Leaf base- The part of the leaf attached to the stem or branch is known as the leaf base. In some plants, like peas and other legumes, the leaf base is swollen.

Petiole - It is the part of the leaf that connects the lamina with the stem. When the petiole is absent, the leaf is sessile. This part is usually cylindrical with a groove on its upper surface.

Lamina- It is the flat, thin, broad, green, and expanded portion of the leaf. The lamina is the most important part of the leaf since it is the seat of food manufacture for the entire plant.

Venation

The arrangement or disposition of veins in the leaf lamina is called venation. The two basic types of venation patterns are reticulate and parallel.

Reticulate venation- When veins are irregularly distributed to form a network, it is known as reticulate venation. This type of venation is a characteristic feature of dicots.

Parallel venation - When veins run parallel to each other and do not form a reticulum, it is known as parallel venation. It is a characteristic feature of monocotyledon leaves.

Types of Leaves

Depending upon the pattern of the lamina, the types of leaves are as follows:

1. In simple leaves, there is a single lamina, which is usually entire or sometimes incised, but incisions never reach up to the midrib.
2. In compound leaves, incisions of the lamina reach up to the midrib, and the lamina is divided into several small segments known as leaflets. They are distinct and remain free from one another, but are joined at the tip of the petiole.

Phyllotaxy

Phyllotaxy is the mode of arrangement or distribution of leaves on the stem and its branches. This arrangement is to make sure that leaves receive the maximum amount of sunlight. Three main types of phyllotaxis are observed in plants: alternate, opposite, and whorled.

1. Alternate- In alternate phyllotaxy, only one leaf is present at each node. Examples- China Rose, mustard and sunflower.
2. Opposite- In this type of arrangement, two leaves are present at each node, standing opposite to each other.
3. Whorled - In this type, more than two leaves are present at each node, forming a whorl, as in oleander and Galium, etc.

Modifications of leaves

Leaves are modified into various types. The types of modification of leaves are:

1. Leaf tendrils- Sometimes, leaves are modified into slender, often coiled structures known as tendrils, which help in climbing the plant.
2. Leaf spines- Leaves of certain plants become wholly or partially modified into sharp, pointed structures known as spines.
3. Pitcher- Leaves of some insectivorous plants like Nepenthes are modified into pitcher-lime structures to trap insects. The pitcher contains water and digestive juices, and it captures and digests small insects.

The Inflorescence

• An arrangement of more than one flower is known as an inflorescence.

• Inflorescences range in size from minute to huge, with a few to a very large number of flowers.

• Many flowers in an inflorescence are pollinated by a single visit of an insect. Therefore, it increases the chances of pollination and abundant seed production.

• Based on the order of development of flowers within a cluster, two basic types of inflorescences, racemose and cymose, have been recognised.

Racemose inflorescence - In this type, the floral axis shows growth, producing flowers in order, with the oldest flower at the lowest and the youngest at the uppermost.

Cymose inflorescence- In this, the growth of the main axis is determinate, that is, the development of the first flower limits the apical growth of the main axis, and the other flowers are formed in another sequence.

The Flower

• Flowers are the most beautiful parts of the plants. Morphologically, the flower is considered a shoot in which sepals, petals, stamens, and carpels are lateral organs. It is meant for sexual reproduction.

• A typical flower has four sets of organs known as accessory organs and an inner set known as essential organs.

• The accessory organs are sepals, which together form the calyx and petals that make up the corolla.

• The essential organs of the flower are the stamens, which form the anther, and the carpels, which together form the gynoecium.

Parts of a flower

Calyx: The calyx is the outermost whorl of the flower, and the members are called sepals. Generally, sepals are green and leaf-like and protect the flower in the bud stage. Sepals are of two types :

Polysepalous- When the sepals are free, for example, Brassica.

Gamosepalous- When the sepals are fused, for example, Dianthus.

Corolla: The Corolla is composed of petals. Petals are usually brightly coloured to attract insects for pollination. There are two types:

Polypetalous - When the petals are free, for example, Brassica.

Gamopetalous- When the petals are united, for example, Ipomoea.

Androceium: (i)The androecium consists of one or more stamens, the male reproductive structures of the flower.

(ii) The stamen is a typically slender organ and consists of two parts, the filament and the anther.

(iii) The anther usually consists of four microsporangia, which contain many pollen grains.

Gynoecium: (i) The gynoecium, made up of one or more carpels, is the female reproductive organ of the flower.

(ii) The carpel is divided into an ovule-bearing part, the ovary; a pollen-receptive part, the stigma; and a sterile part, the style.

(iii) The ovary has one or more chambers known as locules.

Important Terms in the Description of a Flower

Given below are some important terms that are used to describe different types of flowers and their characteristics.

Complete and incomplete flowers

Complete- A flower having all four whorls, that is, the calyx, corolla, androecium, and gynoecium, is called complete.

Incomplete- If one or more whorls are missing in a flower, then it is said to be incomplete.

Symmetry

In symmetry, flowers may be actinomorphic, zygomorphic, or asymmetric.

Actinomorphic- When a flower can be divided into exactly equal halves by a vertical section in any plane, it is said to be actinomorphic. Example - Tomato, mustard.

Zygomorphic- When a flower can be divided into two similar halves by a vertical section in one plane only, it is said to be zygomorphic. Example- pea

Asymmetric- When a flower cannot be divided into two halves by any vertical plane, it is said to be asymmetric. Example- Maranta.

Relative position of Floral parts on the Thalamus

Based on the relative position of floral parts on the thalamus, flowers are of three kinds:

Hypogynous- The flower is said to be hypogynous if sepals, petals, and stamens are inserted below the ovary. Example- mustard.

Perigynous- In rose, the thalamus forms a cup-shaped structure around the ovary and sepals, petals and stamens appear to be inserted. Such flowers are known as perigynous.

Epigynous- When the thalamus completely encloses the ovary and fuses with the ovary wall and sepals, petals and stamens seem to rise above the ovary, the flower is said to be epigynous. Example- apple.

Aestivation

The mode of arrangement of sepals/ petals in a floral bud with respect to the other membranes of the same whorl is said to be aestivation. The following types of aestivation have been recognized.

Valvate - When the members of a whorl are in contact with each other by their margins, without overlapping or turning. Example- Mustard.

Twisted- When the members of a whorl are rolled up in such a way that one margin of a member covers a margin of the next member and the other is covered by the one before it. Example- Hibiscus.

Imbricate- In imbricate aestivation, one member of the whorl is exterior, one interior, and the rest three having one margin exterior and one margin interior. Example- Cassia

Vexillary - Of the five petals, the posterior one is the largest and nearly covers the two lateral petals which in turn overlap the two smallest anterior petals. Example- pea.

Placentation

The arrangement of ovules within the ovary is referred to as placentation. There are several varieties of placentation which are marginal, axile, parietal, basal, central, and free central.

• The placenta forms a ridge along the ventral suture of the ovary in marginal placentation, and the ovules are carried in two rows on this ridge, as in pea.
• The placentation is considered to be axile when the placenta is axial and the ovules are linked to it in a multilocular ovary, as in the china rose, tomato, and lemon.
• Ovules form on the inner wall of the ovary or on the peripheral region in the parietal placentation.
• The placentation is called free central when the ovules are carried on the central axis with no septa, as in Dianthus and Primrose.
• As in sunflower and marigold, the placenta forms at the base of the ovary and is connected to a single ovule in basal placentation.

Representation of floral formula

(A) The floral formula is written in coded form, and it enables us to work out the structure of the flower.

(B) A floral diagram and a floral formula are offered after discussing various components of the plant.

(C) Br stands for bracteate, K for calyx, C for corolla, P for perianth, A for androecium, G for Gynoecium, G for superior ovary, and Ḡ for inferior ovary; ♂ for male, ♀ for female, ⚥ for bisexual plants, ⊕ for actinomorphic, and % for zygomorphic flower. Fusion is represented by enclosing the figure within a bracket, and adhesion is represented by a line drawn above the floral part symbols.

(D) A dot on the top of the floral diagram indicates the position of the mother axis in relation to the flower.

(E) The calyx, corolla, androecium, and gynoecium are drawn in whorls, with the calyx on the outside and the gynoecium in the centre.

The Fruit

• The fruit is a mature or ripened ovary.

• It is formed after fertilisation, which provides a stimulus to the ovary to grow into a fruit.

• A fruit consists of a pericarp that develops from the ovary wall and a seed derived from the ovule. The pericarp may be thin or thick.

• The pericarp is differentiated into epicarp, a middle mesocarp, and an inner endocarp.

• When a fruit develops exclusively from the ovary, it is said to be a true fruit. Mango, guava, grapes, etc., are common examples of true fruits.

• But when, in addition to the ovary, some other floral parts like tepals, bracts or thalamus also participate in the formation of the fruit, then it is said to be known as false fruit. Apples, pears, ananas, etc., are some well-known examples of false fruits.

The Seed

• The seed is a fertilized mature ovule that possesses an embryonic plant, usually stored food material, and a protective coat.

• The seed remains attached to the placenta through a small stalk-like structure known as a funicle.

• Based on the number of cotyledons present, seeds are classified into (i) dicotyledonous seeds and (ii) monocotyledonous seeds.

Structure of a dicot seed

The dicot seeds have two cotyledons and are covered by a hard seed coat.

Seed coat - The seed coat has two integuments, the outer testa and the inner tegmen. The testa is reddish black and thick, while the tegmen is whitish and thin.

Embryo- The entire fleshy body, as seen after removing the seed coat, is the embryo of the baby plant. It consists of two fleshy cotyledons and a short axis to which the cotyledons remain attached laterally. The radicle and the plumule are located at the two extremities of the embryonal axis.

Structure of a monocot seed

The maize grain is a monocot seed where the pericarp is fused with the seed coat.

Seed coat- It is represented by a thin layer that surrounds the grain. This layer is made up of the seed coat and pericarp fused together.

Endosperm- Inside of it, the grain is divided into unequal portions, endosperm and embryo. The larger portion, which lies towards the broader side of the grain, is endosperm.

Embryo- It consists of a single cotyledon and a short axis. The upper part of the axis with minute leaves is known as the plumule, and the lower part is called the radicle.

Also, Read

• NCERT Notes for Class 11 Physics
• NCERT Notes for Class 11 Chemistry
• NCERT Notes for Class 11 Mathematics

Morphology Of Flowering Plants Previous Year Questions and Answers

Some of the questions that have come in past years from the chapter are given below. By referring to the NCERT Class 11 Biology Chapter 5 Notes, students can easily solve these questions.

Question 1. Which of the following plants is used to extract the blue dye?

Option 1. Trifolium

Option 2. Lupin

Option 3. Indigofera

Option 4. Cassia

Answer :

Indigo is a natural blue dye historically derived from the plant Indigofera, most commonly Indigofera Tinctoria, a genus of flowering plants in the Family Fabaceae. The leaves of Indigofera contain a chemical that turns blue on exposure to air. Blue dye is widely used in textile industries as a dye for cotton yarn, primarily in the production of denim cloth suitable for blue jeans.

Hence, the answer is option (3) Indigofera

Question 2. The placenta is attached to the developing seed near the

Option 1. Hilum

Option 2. Testa

Option 3. Micropyle

Option 4. Chalaza

Answer :

The scar on the seed coat through which the seed attaches itself to the fruit is known as the Hilum. Chalaza is the base of the ovule, Testa is the outer covering of the seed, and lastly, micropyle is a tiny opening in the seed coat through which water gets absorbed into the seed.

Hence, the answer is option (1) Hilum

Question 3. Endosperm, a product of double fertilisation in angiosperms, is absent in the seeds of

Option 1. Coconut

Option 2. Maize

Option 3. Orchids

Option 4. Castor

Answer :

The endosperm may be completely consumed by the developing embryo (e.g., pea, groundnut, beans) before seed maturation. Such seeds are called non-endospermic or exalbuminous. It may persist in the mature seed (e.g. castor and coconut) and be used up during seed germination. Such seeds are called endospermic or albuminous. The embryo in the orchid plant absorbs the endosperm during growth.

Hence, the answer is option (3) Orchids

Also Read:

• NCERT Solution
• NCERT Solutions for Class 11
• NCERT Solutions for Class 11 Biology

NCERT Class 11 Biology Chapter-wise Notes

The chapter-wise notes are given below: