Chemical Coordination in Plants

Movement In Plants

In animals, control and coordination is governed by the nervous system. However, plants do not have a nervous system.

Then, how do plants respond to stimuli?

Plants respond to stimuli by showing movement.

Have you ever seen any movement in plants?

• When you touch a sensitive plant such as touch- me- not (Mimosa pudica), the plant folds its leaves and droops.

• When a seed germinates, the root grows down in the soil and the stem grows up in the air.

In the first example, touch is the stimulus and the plant responds by folding its leaves. Therefore, the plant shows movement by folding its leaves.

In the second example, the seed germinates and shows directional movement.

In the first example, movement is independent of growth i.e. there is no growth involved. However, in the second example, the movement of the seedling is caused by growth. If the seedling is prevented from growing, then it will not show any movement.

Thus, plants exhibit both growth-dependent and growth-independent movements.

Growth-independent movements

In plants (like animals), the information is carried from cells by electro-chemical means. However, there is no specialized tissue for the conduction of information. In fact, plants change their shape by changing the amount of water in them. This results in swelling and shrinking. This change of shape results in movement.

Growth-dependent movements

You must have seen plants such as peas and grapes with tendrils. Movement in these plants occurs in the growing stem of the tendrils. When the tendrils come in co…