Plant Profiles: Touch-Me-Not - (Mimosa pudica)

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Mimosa pudica goes by many different names, touch-me-not, sensitive plant, humble plant, shame plant, and many more, however, every name has one thing in common - they allude to the fact that this plant can move on its own. A perennial member of the legume family, this plant's leaves fold together and droop under two circumstances. Pudica leaves fold and droop every night when the sun has set. Called Nyctinastic movements, there are suggestions that this is done to conserve heat and water during the night.

The second, and more well-known, type of movement that pudica exhibits is seismonastic movement, which is the result of the plant being touched, such as a person rubbing their fingers against the leaves. A touch causes potassium and other ions to be released and subsequently cause the water within the cells to exit them. The loss of this water pressure, called turgor pressure is the mechanism by which the plant closes its leaves. Considering the large energy cost, scientists are still debating the reasons for the evolutionary development of such a mechanism. It's possible that the movement scares away herbivores who might be interested in a quick meal, it could also startle insects that land on its leaves.

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