Mimosa somnians

Mimosa somnians, the sleeping sensitive plant or dormideira, is a perennial herb to small shrub in the family Fabaceae (subfamily Mimosoideae) native to tropical South America, particularly Brazil, Bolivia, Paraguay, and northern Argentina, and naturalized in parts of Central America and the Old World tropics. It typically grows 0.3-1.5 m tall with slender, branched, prickly to bristly stems. Like other sensitive mimosas, the leaves are bipinnately compound and conspicuously thigmonastic — the small leaflets fold rapidly together when touched, mechanically disturbed, or at nightfall (hence the epithet somnians, "sleeping"). Each leaf typically bears 2-6 pairs of pinnae, with many small, oblong leaflets 3-8 mm long. The inflorescence is a small, globose to ellipsoid pink to lilac head of many small, four-merous flowers with conspicuous protruding stamens, borne in the upper leaf axils. The fruit is a flat, jointed, bristly legume (craspedium) that breaks transversely into one-seeded segments at maturity. It grows in open, disturbed, sunny habitats from sea level to mid-elevations.