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Mimosa Plant (Mimosa pudica): How It Moves its Leaves
Mimosa Plant Motor Movements
The Mimosa Plant
The Mimosa plant (Mimosa pudica) also known as “touch-me-not” means “mimicking shy”. This name derived from Greek and Latin came about because of the plants curious motor movements. Far more interesting than the Venus flytrap, the Mimosa promptly closes its leaves if it is touched or shaken. If the touch is strong enough the entire plant ends up folding its leaves together leaving the Mimosa almost unrecognizable potentially providing safety from foragers.
Why Does The Plant Move?
It is thought that the Mimosa plant moves as a defense mechanism. For example, it would be beneficial for the Mimosa to close its leaves if a caterpillar climbed on it. Instead of eating the leaves, the caterpillar might be stuck inside the leaf, or it might fall off the plant. Closing the leaves also makes the plant look less appetizing to passing herbivores and prevents water loss at night.
How Does The Mimosa Move?
There are two cases that cause the Mimosa to close its leaves. Do not imagine that the plant has a central nervous system, neurons and all, that allow it to sense when it is in danger. Nyctonastic movements, which are reactions that happen in absence of light, cause the Mimosa to close its leaves at night.
Chemical responses also enable the Mimosa plant to close its leaves when it is touched. Specialized tissue moves potassium, K+, ions from one cell to another and a pressure response builds that squeezes the plant shut. This pressure is called Turgor pressure and it can happen because Mimosas and all plants have cell walls which are rigid enough that they prevent the cell from blowing up when it swells, but flexible enough to allow it to move just enough for it to be able to shut its leaves.
Mimosa pudica (many seeds)
How long does the Mimosa stay closed?
At night, the entire plant closes its leaves. During the daytime the Mimosa’s leaves remain open unless there is a stimulus. The leaves reopen a few minutes after the stimulus is gone.
Where Is The Mimosa Found?
The species is native to South America and Central America, but can readily be purchased at Garden Shops.