sensitive plant

from The American Heritage® Dictionary of the English Language, 4th Edition

• n. A shrubby tropical American plant (Mimosa pudica) having mauve flower heads and bipinnately compound leaves with leaflets and leafstalks that fold and droop when touched. Also called touch-me-not.
• n. Any of various similar plants, such as Cassia nictitans, of eastern and central North America.

from the GNU version of the Collaborative International Dictionary of English

• adj. Any plant showing motions after irritation, as the sensitive brier (Schrankia) of the Southern States, two common American species of Cassia (C. nictitans, and C. Chamæcrista), a kind of sorrel (Oxalis sensitiva), etc.

from The Century Dictionary and Cyclopedia

• n. The tropical and greenhouse plant Mimosa pudica; the humble-plant.
• n. Same as sensitive pea (which see, under pea).
• n. The narrow-leaved sensitive-brier, Leptoglottis angustata (Schrankia angustata of Torrey and Gray), found from Virginia to Florida aud west to Tennessee and Texas.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• n. semi-climbing prickly evergreen shrub of tropical America having compound leaves sensitive to light and touch
• n. prostrate or semi-erect subshrub of tropical America, and Australia; heavily armed with recurved thorns and having sensitive soft grey-green leaflets that fold and droop at night or when touched or cooled