Mimosa pigra L. var. pigra
Family Fabaceae, Subfamily Mimosoideae
one-seeded fruit segment
Fruit a craspedium; craspedia linear-oblong, compressed, straight or curving slightly, 4–7.5 cm long, 8–11 mm wide, ca. 2 mm thick. Sessile, apex mucronate, margins straight. Densely bristly. At maturity narrow 1-seeded fruit segments (valves) split transversely and separate from the persistent sutures. Valves 20–25.
Seeds oblong in outline, umbo absent, 4–8 mm long, 2–4 mm wide, 1.75–2 mm thick, depressed on faces, irregularly oblong in cross section. Dull, semiglossy, smooth. Pleurogram open, distinctly wide and closely following margin; pleurograms on each face nearly connected at base. Lens elliptic, same color or lighter than testa, surrounded by darker halo, flush or slightly raised. Embryo investing, cotyledons much longer than radicle.
Seeds distinctly oblong, with a wide pleurogram.
United States, Mexico through Central America and the Antilles; South America: Colombia, Peru, and Brazil to northern Argentina. In the eastern hemisphere, Africa: Ghana, Madagascar, Mauritius, Nigeria, South Africa; Asia: Cambodia, Indonesia, Philippines, Sri Lanka, Taiwan, Thailand; Oceania: Australia, Fiji, Hawaii, Polynesia
native to tropical America
wet places in the humid and subhumid tropics, such as drainage ditches, wetlands, riverbanks, and lowland fields
Mimosa pigra is a prickly shrub, 3–5 m tall, that forms impenetrable thickets, making areas inaccessible to humans and animals. Reproduction is by seed and vegetatively from cut stems. The hairy one-seeded craspedium segments stick to animal fur and are eaten by animals. But more significantly, the segments float, allowing the plant to be dispersed by flood waters and along river systems, enabling it to rapidly colonize large wetland areas. This shrub interferes with irrigation projects and smothers pasture lands.