Mimosa pudica is an annual or perennial herb native to South America and Central America. The plant is also found in some of the Asian countries and called with different names like sensitive plant, sleepy plant or shy plant. The word ‘pudica ‘ is a Latin word which means ‘shy’. Mimosa Pudica is most popularly called Touch-me-not and belongs to the pea family Fabaceae. The stem of the plant is erect when young but becomes a creeper as it grows. The plant has multiple prickles and the leaves are bipinnately compound.
The unique feature of Mimosa pudica that makes it different from other plants is it’s response to external stimuli. The leaves close during darkness and reopens in light, this behaviour is called “sleep” or nyctinastic movement. The leaves also close in response to various other stimuli, like touch, heat, movement (shaking) etc. These typical movements exhibited by Mimosa pudica are called seismonastic movements. This particular movement is believed to be a kind of defensive mechanism to scare off insects or predators. When the leaves of this plant are touched, the leaflets fold inward. Further disturbances on the plant makes it move downwards to reveal its thorns. This kind of movement occurs due to some chemical reactions that take place in the cells that results in loss of cell pressure. It takes around 20 minutes for the plant to get back its leaves to normal.
Mimosa pudica is mostly grown as an ornamental plant. Belonging to the legume family, the plant is capable of hosting nitrogen-fixing bacteria in the root nodules. This bacteria can convert atmospheric nitrogen, which plants cannot use, into a form that plants can use. This plant also has several medicinal uses.