Question

Rohan touched the leaves that touched me, not plants and the leaves dropped. Give the reason for the change.

Answer 1

Hint: Mimosa pudica is also called Touch me not plant. This plant shows seismonastic movement. It is a nastic movement in which the plants respond to the stimulus irrespective of the direction of the stimulus.

Complete Answer:
 Touch me no plant is sensitive to touch. The plant uses this ability as a defence mechanism from the herbivores. This sudden movement prevents the plant from harmful insects.

Mechanism: The main structure responsible is the pulvinus. The stimulus or the action potential is generated at the leaflet which moves to the swollen base and from there it transmits to the pulvini of other cells. It further passé to the petiole where it is attached to the stem. Touching generates stimulus. This stimulus reaches the base of the leaf and the vacuoles lose water to the adjacent cell. The cell becomes flaccid. This causes the leaves to close. This causes a change in turgor pressure. The turgor pressure at the lower half of the pulvinus is reduced as a result of which the leaf droops.

Note: Mimosa belongs to the sub family Mimosaceae. It is a tropical creeping plant. The seismonastic movement shown by the leaves is very unique and used widely for research. The plant is used in ayurveda as a medicine to treat leprosy, dysentery, burning sensation and also to treat certain female reproductive disorders. The leaves closes due to stimulus and reopens again in a few minutes.