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Posted by on Sep 22, 2015 in Tell Me Why |

Why Do the Mimosa’s Leaves Close When Touched?

Why Do the Mimosa’s Leaves Close When Touched?

The mimosa plant is a touchy plant. It is so sensitive that it closes up when touched. The leaves of certain mimosas contain a special kind of cell. When something touches these leaves, the special cells lose some of their water. The cells shrink, causing the leaves to fold together.

At the same time, the leafstalks bend back toward the main stem, as if the plant were shrinking from being touched. If the plant is left alone, these cells again fill with water and the leaves open. Plants that react this way belong to a group called “sensitive plants.”

The exact reason for this peculiar behavior of the mimosa plant is unknown, but it is believed the plant uses this feature to thwart predators. The closing leaves supposedly scare them away.

Apart from the stimulus of human touch, the leaves also close during night time. The plant has its origins in South and Central America, but it is actually found all around the world.

The closing motion of the leaves is what makes this plant so special. Mimosa is popular as an ornamental plant, but needs to be handed with caution. A plant that is so sensitive to touch can actually be poisonous if ingested. It is especially dangerous for children who find it to be an object of great fascination.

Content for this question contributed by Marsha Amman, resident of Pittsburgh, Allegheny County, Commonwealth of Pennsylvania, USA