Plant Structure and Its Functions

Plants which produce flowers are known as flowering plants. Parts of the plant body mainly concerned with nutrition and growth are called vegetative parts. The vegetative parts of the plant comprise the root system and partly, the shoot system.

The root system with its differentiated parts performs two primary functions: fixation and absorption.

The vegetative shoot consisting of the main stem, branches and leaves has mainly three functions: support, conduction and food manufacture (primarily by leaves).

The reproductive shoot is the flower with its differentiated organs. It is essentially concerned with the reproduction of the plant.

Plants on the basis of size and the nature of their stem, can be classified into three categories-

1. Small plants/herbs: A banana tree has a green, soft stem. It is actually the biggest herb.

2. Medium plants/shrubs

3. Big plants/trees

1.0Comparison of Plants on the Basis of Size

2.0Design of Plant Body

3.0Root System 

The root system is the underground part of the plant consisting of the root and its branches.

Characteristics of the Root

(1) The root develops from the radicle of the seed.

(2) It is non-green.

(3) It grows towards the soil i.e., towards gravity (geotropic).

(4) It grows towards water (hydrotropic).

(5) It grows away from light.

(6) It does not bear nodes, internodes, leaves, flowers and fruits.

4.0Shoot System 

The shoot is the aerial part of the plant consisting of the stem, leaves, branches, flowers and fruits.

Stem

The stem is the main axis of the shoot system that bears nodes, internodes, buds and holds up the leaves, branches, flowers and fruits.

Characteristics of the Stem

1. The stem develops from the plumule of the seed.

2. Young stems are green while the older, woody stems are non-green.

3. Stems grow towards sunlight.

4. Stems grow away from soil and water.

5. Stems may be branched or unbranched.

6. Stems have nodes and internodes.

7. Buds occur at the apex (tip) of the stem (terminal bud) and in the axil of leaves (axillary bud).

Leaf

The leaf is a flat, green, lateral growth arising from the node of the stem. The wide flat green portion of the leaf is called lamina or leaf blade. 

The thin portion of leaf by which it is joined to the stem is called stalk or petiole. The petiole extends into the leaf as the midribs and joins the stems at the leaf base. The thin lines that arise from the petiole and midrib and spread across the leaf are called veins. The veins branch into veinlets. The veins provide support to the leaf and carry water, minerals and food.

The arrangement of veins on a leaf is called venation. There are two types of venation: Parallel venation and reticulate venation.

The Flower

Sexual reproduction takes place through the agency of flowers in angiosperms (flowering plants).

Flower is a specialized condensed reproductive shoot of flowering plants on which the essential reproductive parts are inserted.

Fruit

A fruit is a ripened ovary formed after fertilization. 

Functions of fruits:

(i) The fruit wall gives protection to the seeds and therefore, to the embryo in two ways.

When young, its green color keeps it hidden under the green foliage, and

When mature, its coloured, soft and fragrant fruit wall attracts the agents for the dispersal of fruits and seeds. 

(ii) The fruit is a store house of food material.

(iii) The fruit helps in the dispersal of seeds.

(iv) We eat fruits such as peaches, apples, tomatoes, brinjals etc.

Note: Clove is an edible flower bud.

Seeds

A seed is a fertilized ripened ovule. Seeds contain the embryo (future plant) and stored food. The seed is covered by a tough covering called the testa. Food may be stored in a persistent endosperm or a thick, fleshy, wing-like structure called the cotyledon.

Edible seeds are Fenugreek, Sesame, Cardamom, Cumin, Rajma, Pea, Soyabean etc.

5.0Related Questions

1. Tap roots are present in

Ans. Carrot 

2. A plant having parasitic roots is 

Ans. Dodder

3. Wheat is a 

Ans. Herb

4. Fibrous roots are present in

Ans. Wheat

5. Photosynthetic roots are found in which plant.

Ans. Tinospora

6. Roots which appear like a cluster.

Ans. Fiborous

7. Plants which fix nitrogen in the soil.

Ans. Leguminous

8. Type of root present in Cuscuta. 

Ans. Parasitic Root

9. Stem develops from the ______of the seed.

Ans. Plumule

10. Pollen grains ripe to form fruit.

Ans. False

11.     Seed is a fertilized ripened ovule.

Ans. True

12. A fruit is a ripened ovary formed after fertilization.

Ans. True

13. The anther and filament are connected by a connective tissue.

Ans. True

14. Leaves are modified to spines to reduce water loss.

Ans. True

6.0Also Read