Morphology Of Flowering Plants Class 11 Notes Biology Chapter 5 - CBSE

Chapter : 5

What Are Morphology Of Flowering Plants?

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Morphology

Morphology is the branch of biological science that deals with the study of form, size, colour, structure and relative position of various parts of organisms.

The Root

It is the underground part formed from radicle of embryo. Root systems are three types :

Tap root system: It consists of primary roots (tap root) and its branches (lateral roots such as secondary roots, tertiary roots). Seen in dicots. Primary root is elongated from radicle. E.g. Mustard plant.
Fibrous root system: In monocots, primary root is short lived and is replaced by many roots. They originate from the base of stem to form fibrous root system. E.g. Wheat.
Adventitious root system: Roots that arise from parts other than radicle. E.g. Grass, Monstera and banyan tree.

Regions of the Root

Root cap: It is the covering at the apex of root. It protects the tender apex of the root.
Region of meristematic activity: Seen above the root cap. Here, the cells are very small, thin-walled and with dense protoplasm. They divide repeatedly.
Region of elongation: Region just above the meristematic region. Here, cells undergo rapid elongation and enlargement. Helps in growth of the root in length.
Region of maturation: It is proximal to elongation zone. Here, the cells differentiate and mature.
Root hairs: Very fine, delicate, thread-like structures formed from epidermal cells inregion behind the region of elongation. They absorb water and minerals from the soil.

Modifications of Root

In some plants, roots are modified to perform functions other than absorption and conduction.

Swollen roots: For food storage: E.g. Tap roots of carrot, turnips and adventitious roots of sweet potato.
Prop roots: Hanging structures that support banyan tree.
Stilt roots: The supporting roots coming out of the lower nodes of the stem. E.g. maize and sugarcane.
Pneumatophores: The roots that come out of the ground and grow vertically upwards to get oxygen for respiration. E.g. Rhizophora growing in swampy areas.

The Stem

It is the ascending part of the axis that develops from the plumule of the embryo of a germinating seed.

Modifications of Stem

For food storage: E.g. underground stems of potato, ginger, turmeric, zaminkand, Colocasia etc. They also
act as organs of perennation to tide over conditions unfavourable for growth.
Stem tendrils: Slender and spirally coiled structures formed from axillary buds. They help plants to climb.
E.g. Gourds (cucumber, pumpkins, watermelon) and grapevines.
Thorns: Woody, straight and pointed structures developed from axillary buds. They protect plants from browsing animals. E.g. Citrus, Bougainvillea.
Phylloclade: It is a green, flattened or fleshy cylindrical stem containing chlorophyll for photosynthesis. Found in some plants of arid regions. E.g. Opuntia (flattened stem), Euphorbia (cylindrical stem).
Stolon: Slender lateral branch that arises from the base of the main axis and after growing aerially for some time arch downwards to touch the ground. E.g. mint and jasmine.
Offset: It is a lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots . E.g. aquatic plants like Pistia and Eichhornia.
Sucker: The lateral branches that originate from the basal underground part of the main stem. It grows
horizontally beneath the soil and come out obliquely upward giving rise to leafy shoots. E.g. Banana, Pineapple and Chrysanthemum. Underground stems of grass, strawberry etc. spread to new niches. When older parts die, new plants are formed.

The Leaf

It is a lateral, flattened structure borne on the stem. They are important vegetative organs for photosynthesis. A typical leaf has 3 main parts.

Leaf base: With this, the leaf is attached to stem. It may bear two lateral small leaf-like structures called stipules. In monocots, the leaf base expands into a sheath covering the stem partially or wholly. In some leguminous plants, the leaf base may be swollen.
Petiole: It helps to hold the leaf blade to light. Long thin flexible petioles allow leaf blades to flutter in wind, thereby cooling leaf and bringing fresh air to leaf surface.
Lamina (leaf blade): The green expanded part with veins and veinlets. The middle prominent vein is called
midrib. Veins provide rigidity to lamina and act as channels of transport for water, minerals and food materials.

Venation

It is the arrangement of veins and veinlets in leaf lamina. It is 2 types.

Reticulate venation: Here, the veinlets form a network. It is seen in dicotyledons.
Parallel venation: Here, the veins run parallel to each other within a lamina. It is seen in monocotyledons.

Phyllotaxy

It is the pattern of arrangement of leaves on the stem or branch. It is of three types.

Alternate: In this, a single leaf arises at each node in alternate manner. E.g. China rose, mustard.
Opposite: In this, a pair of leaves arise at each node and lie opposite to each other. E.g. Calotropis and guava.
Whorled: In this, more than two leaves arise at a node and form a whorl. E.g. Alstonia.

Modifications of Leaves

Leaves are modified to perform functions other than photosynthesis.

Tendrils: For climbing. E.g. peas.
Spines: For defense. E.g. cacti.
Fleshy leaves: To store food. E.g. onion and garlic.

Inflorescence

It is the mode of arrangement of flowers on the axis of the plant.
The common axis which bears inflorescence is termed as peduncle but the stalk of the individual flower of the inflorescence is called a pedicle.

Types Of Inflorescence

Racemose

It is a type of an inflorescence where the main axis continues to grow indefinitely and does not terminate in flower.

Cymose

This inflorescence is characterised by the presence of a flower at the apex of the flower axis.

Flower [bisexual Type]

Calyx

(Constituent unit is sepals)

Functions
Sepals protect the flower in the bud stage
Green calyx produce food.
Attracts the insects for pollination.

Corolla

(Constituent unit is petals)
Functions
In the bud stage ,the corolla protects the
inner essential organs.
Attracts the insects for pollination.

Androecium

(Constiuent units are stamens)

Filament
Anther
- Functions
  - Powdery pollen grains are produced which have male gametes and is released for pollination.
Connective
Gynoecium

(Constiuent units are carpels)

Stigma

Functions
- Flattened, Sticky or feathery part
  adapted Style to receive pollen grains.
Style
Ovary
- Functions
  - Female gametes are developed.
Ovule

Flower

A flower is a modified shoot in which the internodes are highly condensed and the leaves are modified into floral parts.

Some Facts About Flower

Sepaloid petals: Green colour petals are called Sepaloid petals.
Monoecious: When both the male and female flowers are present on the same plant, the plant is called monoecious. E.g. Pumpkin, maize etc.
Dioecious: When either the male or female flower is present on the plant, the plant is called dioecious.
E.g. mulberry, date palm etc.
Incomplete flower: When any one of the whorls is missing in a flower, it is called an incomplete flower.
E.g. Cucumber, bottle gourd.
Bisexual flower: When both reproductive whorls are present. E.g. Rose, sunflower.
Neuter flower: When both reproductive whorls are absent. E.g. Ray florets of a sunflower plant.
Nectaries are common in bright colour flowers.

The Fruit

It is a ripened ovary developed after fertilisation. It is a characteristic feature of the flowering plants. If a fruit is formed without fertilisation of the ovary, it is called a parthenocarpic fruit. A fruit consists of:

Pericarp (fruit wall): It may be dry or fleshy. When pericarp is thick and fleshy, it is differentiated into outer epicarp, middle mesocarp and inner endocarp.
Seeds: In mango, the pericarp is well differentiated into thin epicarp, fleshy edible mesocarp and stony hard
endocarp. In coconut, the mesocarp is fibrous.

Family Solanaceae

Plant body herbs or shrubs, rarely small trees, commonly known as potato family. Leaves simple or pinnately compound. Reticulate venation. Floral Formula: K₅ C₅ A₅ G₂ .