sensitive plant

1. Also called humble plant. a tropical American plant, Mimosa pudica, cultivated in greenhouses, having bipinnate leaves whose leaflets fold together when touched.

2. any of various other plants that are sensitive to touch.

[1650-60]

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Either of two plants in the pea family (see legume) that close up their leaves and droop when touched.

This unusually quick response is due to rapid water release from specialized cells at the bases of leaftsalks. The more common plant is Mimosa pudica (see mimosa). Spiny and shrubby, with fernlike leaves and small, globular, mauve flower puffs, it grows about 1 ft (30 cm) high as a widespread tropical weed and a greenhouse curiosity. Wild sensitive plant (Cassia nictitans) is less sensitive to touch; a larger plant, 20 in. (50 cm) high, it is native to the eastern U.S. and the West Indies.

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▪ botany

      either of two plants, in the pea family (Fabaceae), that respond to touch and other stimulation by closing up their leaves and drooping. The more common plant is Mimosa pudica, also called humble plant. A spiny, shrubby plant growing to a height of about 30 cm (1 ft), it has fernlike leaves and small, globular, mauve flower puffs. A widespread weed in tropical regions, it is naturalized elsewhere in warm areas and is grown as a curiosity in greenhouses. The plant's unusually quick response to touch is due to rapid water release from specialized cells located at the bases of leaflet and leaf stalks.

      Wild sensitive plant (Cassia nictitans), up to 50 cm, also exhibits sensitivity to touch but to a lesser degree. It is native to the eastern U.S. and the West Indies.

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