Question

Desmodium gyrans show the movement of leaflets. This type of movement is
(a) Nastic movement
(b) Curvature movement
(c) Movement of variation
(d) None of the above

Answer 1

Hint: A slight change in its movement that occurs rapidly depending upon the presence of light energy that is resulted from the sensory movement in the plants and helps in performing various metabolic reactions.

Complete answer:
Desmodium gyrans show the movement of leaves which is called the movement of variation. The plant is commonly known as Indian telegraph plant or a dancing plant.
 - Desmodium is botanically known as Codariocalyx motorius.
- It is the group of few plants which show rapid movement including Mimosa pudica, and the Venus flytrap.
- The plant is small and has purple flowers.
- The leaves move at rapid speeds to maximize the light at the trophic level.
- Each leaf absorbs more energy because the weight of the leaves is more and the plant needs to spend more energy for its movement.
- These movements may form a butterfly mimicry which stops the eggs of the butterflies in the leaves.
- The leaves rotate about 3-6 minutes.
- The plant is described in detail in Charles Darwin The Power of Movement in plants'
- The movement of variation in the curvature of the bending of the plant part is temporary.
- The movement of variation involves the up and down movements which occur in the lateral leaflets.
- This movement is the result of the presence of the motor cells that are found at the base of the leaflets.
So, the correct answer is ‘Movement of variation’.

Note: The plant Desmodium gyrans is described in detail in 1880 by Charles Darwin, in his book ‘The Power of Movements in Plants’. It has been used as an ornament in a garden. They are erect plants but totally on their axes and move up and down under the influence of the sunshine.