虱子草 shi zi cao

Tragus racemosus (Linnaeus) Allioni var. berteronianus (Schultes) Hackel; T. tcheliensis Debeaux.

Annual, mat-forming. Culms tufted, usually decumbent at base and rooting at lower nodes, 15–30 cm tall. Leaf sheaths shorter than or subequal to internodes; leaf blades broadly linear, tough, flat, glaucous, 3–7 cm, 3–4 mm wide, margins thick, pectinate-spinose, apex acute. Inflorescence 4–11 × ca. 0.5 cm; racemes of 2 unequal spikelets separated by a 0.4–0.6 mm rachis internode; rachis not extended beyond upper spikelet; basal peduncle 0.2–0.4 mm. Lower spikelet fertile, elliptic, 2–3 mm; lower glume suppressed; upper glume 5-ribbed, ribs bearing hooked, swollen-based spines, apex acute; lemma ovate-lanceolate, 1.8–2.1 mm, puberulous, apex sharply acute. Upper spikelet sterile, narrowly elliptic, 1.5–2.2 mm, often reduced to the upper glume. Fl. and fr. summer to autumn. 2n = 20.

Roadsides, other weedy places. Anhui, Gansu, Hebei, Jiangsu, Nei Mongol, Shaanxi, Sichuan [Afghanistan, Pakistan; Africa, America, SW Asia].