Question

What is 'Pulvinus' in leaves? In which plants is it found? What are their functions?

Answer 1

Pulvinus:

1. Pulvinus is a swollen leaf base composed of tissues that conduct water surrounded by a layer of motor cells.
2. The motor cells can swell or shrink depending on whether the water moves in or out of the cell causing the movement of leaves.
3. The turgidity is altered when the motor cells adjust the potassium ion concentration by either accumulating them or pumping them out.

Examples of plants that have pulvinus:

1. Mimosa pudica displays thigmonasty which means touch-sensitive response.
2. Leguminous plants display nyctinasty which means the leaves of the plant droop when it becomes dark.

Functions of the pulvinus:

1. The function of the pulvinus is demonstrated accurately in the Mimosa pudica plant.
2. In Mimosa pudica, the leaves display movements induced by touch, also known as thigmonasty.
3. When the leaves are touched, an electrical signal is produced which reaches the motor cells in the pulvinus causing the leaflets to fold.
4. The folding is a result of the pumping out of potassium ions and transport of water out of the motor cells