Mimosa diplotricha

Name and classification

Mimosa diplotricha C. Wright
(=Mimosa invisa Mart.)
Family Fabaceae, Subfamily Mimosoideae

Common names

giant sensitive plant

Disseminule

one-seeded fruit segment

Description

Fruit a craspedium; craspedia clustered, linear-oblong, compressed, straight or slightly curved; (8)10–24(35) mm long, 3–4.2(5.5) mm wide, ca. 1 mm thick. Apex usually fairly long-tapered, margins nearly straight. At maturity fruit splits transversely into (2)3–8 1-seeded segments (valves) that separate from the persistent sutures. Valves with short prickly bristles on margins and surfaces.

Seeds obovate to subrhombic in outline, umbo absent, 2–3(3.6) mm long, 1.9–2.7 mm wide, 0.6–1.4 mm thick, elliptic to narrowly elliptic in cross section. Semiglossy, smooth. Pleurogram average to slightly wide. Lens round to elliptic, flush, whitish, surrounded by dark halo. Embryo investing; endosperm present.

Identification considerations

The bristly craspedium and one-seeded craspedium segments are distinctive. Compare with Mimosa pigra L. var. pigra.

Similar species

See seeds of Prosopis species.

Distribution

widespread in South America, Central America, the West Indies, and Mexico; Hawaii, Puerto Rico; eastern hemisphere: parts of Africa, India, Southeast Asia, Australia, and the Pacific Islands

native to South America

Habitat

moist soils in tropical and subtropical climates; wet waste places and disturbed areas, plantations, pastures, cultivated ground

General information

The original federal noxious weed listing for this weed (by the Technical Committee to Evaluate Noxious Weeds) was for Mimosa invisa Mart., now called Mimosa diplotricha C. Wright. But historical evidence suggests the Technical Committee included Mimosa invisa Mart. ex Colla within their concept of the species. According to Barneby (1987), however, these two are distinct species. APHIS will clarify the listing after conducting a risk assessment on both species.

Mimosa diplotricha is a prickly, erect or prostrate, spreading shrub, up to 2–3 m tall. It scrambles over and smothers other plants by means of its prickly stems. Thickets of the tangled stems can seriously injure humans and trap animals, that may die. This plant is a serious tropical plantation weed in Southeast Asia and the Pacific Islands, infesting rubber, coconut, and sugarcane fields. The seeds are retained in one-seeded valves that are dispersed by sticking to animal fur or by floating on streams.

seeds

seeds

lens (top) and hilum (bottom) of seed

lens (top) and hilum (bottom) of seed

cluster of craspedia

cluster of craspedia

craspedium

craspedium