Question

The pulvinus in ‘touch-me-not plant’ plays an important role in
A. Photosynthesis
B. Leaf fall
C. Leaf movement
D. Transpiration

Answer 1

Hint: The seismonastic or rapid movements in the Mimosa plant or touch-me-not plant is triggered by the sense of touch and temperature. This type of movement prevents the plant from herbivory.

Complete answer: In Mimosa plants, below each leaf, a fluid-filled cavity is present which is known as a pulvinus. Whenever someone touches the Mimosa plant, then electrical signals are transmitted and the pulvinus throws all the liquid out of the cavity. It results in drooping of leaves because of the expulsion of water from the cavity. The pulvinus helps in driving out the most rapid hydraulic motion or movement of leaves. Herbivory can be prevented by this movement. This is a type of adaptation that helps to change the orientation of the leaves.
Hence, the correct option is C-Leaf movement.

Note: The pulvinus is a joint-like bulging structure in Mimosa pudica that connects the mainstem from the petiole. The pulvinus of the petiole helps in the omnidirectional movement of the leaves. The leaves droop as a result of a sense of touch that prevents them from predators and environmental conditions. Therefore, it is also known as a sleeping or sensitive plant. It is a perennial plant that belongs to the family Fabaceae. It has compound leaves that fold inward upon reception of touch to prevent herbivory. It is also known as a humble plant and is usually grown for its curiosity value.