光头稗 guang tou bai

Panicum colonum Linnaeus, Syst. Nat., ed. 10, 2: 870. 1759; Echinochloa crusgalli (Linnaeus) P. Beauvois subsp. colona (Linnaeus) Honda; Milium colonum (Linnaeus) Moench; Oplismenus colonus (Linnaeus) Kunth; P. crusgalli subsp. colonum (Linnaeus) Makino & Nemoto.

Annual. Culms erect or ascending, up to 60 cm or more tall. Leaf sheaths compressed and keeled; leaf blades linear, flat, 3–20 × 0.3–0.7 cm, glabrous, sometimes with transverse purple bands, margins slightly scabrous, apex acute. Inflorescence narrow, 5–10 cm; racemes 1–2 cm, erect or sometimes stiffly diverging, simple, separated or overlapping by up to half their length or more, rachis usually without long, tubercle-based hairs, spikelets tightly congested in 4 neat rows. Spikelets plumply ovate-oblong, 2–3 mm, hirtellous, sharply acute; lower glume ca. 1/2 as long as spikelet; lower lemma staminate or sterile; upper lemma whitish at maturity, elliptic. Fl. and fr. summer and autumn. 2n = 36.

A weed of damp places and irrigated fields. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [warm regions throughout the world].

Echinochloa colona is a widespread, weedy species, distinguished by its short, neat, usually rather openly spaced racemes of rounded, awnless spikelets.