Description

Key Characters:

Growth Form: Creeping annual or perennial herbs.

Stems: Stems 3–15 dm long, sparsely to densely prickly and sparsely hispid to glabrate.

Roots:

Leaves: Leaves compound (bipinnate). Alternate. Leaflets narrowly elliptic. pinnae 1–2 pairs, leaflets 10–26 pairs per pinna. blades sensitive, closing when touched, rachis short, leaflets, 6–15 mm long, 1.2–3 mm wide. Leaflet margins entire. Petioles glabrous or hispid, usually sparsely prickly. Stipules about 7 mm long.

Flowers: Flowers in globose or ovoid, axillary, pedunculate heads, these 1–5 in the leaf axils, 8–10 mm in diameter (excl. stamens), sparsely to densely hispid. Flowers bisexual (perfect), mimosaceous. Calyx mi­nute. Corolla red in upper part 2–2.5 mm long; stamens 4(–6). Stamens 4(–6); filaments pink to lavender, 4.5–6 mm long, distinct, exserted. Ovary superior; style 1, apical.

Fruit: Pods in clusters of 2–8; prickly on the margins; 1–2 cm long; 0.3–0.5 cm wide; breaking into 2–5 segments; indehiscent but separating into 1–seeded segments; leaving the replum intact as an empty skeleton. Seeds pale brown; ca. 2.5 mm long.

Ploidy: 2n = 32; 48; 52; 78

Habitat: Open; dry to wet; disturbed areas; especially lawns.

Elevation Range: 5–700 m.