8. Paspalum distichum Linnaeus, Syst. Nat., ed. 10. 2: 855. 1759.
双穗雀稗 shuang sui que bai
Digitaria paspalodes Michaux; Paspalum paspalodes (Michaux) Scribner.
Perennial with rhizomes and stolons. Culms 20–50 cm tall, nodes usually pubescent. Leaf sheaths keeled, glabrous, margins ciliate; leaf blades linear, 5–10 × 0.3–0.7 cm, glabrous, apex acute; ligule 2–3 mm. Inflorescence of 2(–3) racemes arising together or separated by a short axis; racemes 3–7 cm; spikelets single, in 2 rows; rachis straplike, 1.5–2 mm wide. Spikelets pallid, obovate-oblong, plano-convex, 3–3.5 mm, acute; lower glume vestigial or a narrow triangular scale up to 1/2 spikelet length or more; upper glume papery, 3–5-veined with distinct middle vein, loosely appressed pubescent; lower lemma 3–5-veined, usually glabrous; upper lemma pale green, almost equal to spikelet, cartilaginous, apex apiculate and minutely pubescent. Fl. and fr. May–Sep. 2n = 40, 48, 60.
Fields, roadsides, ditches and other disturbed places, mostly on moist fertile soils. Anhui, Fujian, Guangxi, Guizhou, Hainan, Henan, Hong Kong, Hubei, Hunan, Jiangsu, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang [tropical and warm-temperate regions of the world].
The length of the lower glume is very variable, even within a single raceme. The spikelets are not obviously hairy because the pubescent upper glume faces inward, but the creeping habit together with paired racemes of plump spikelets are distinctive. Rarely the upper glume is glabrous, but such specimens can be separated from the closely related Paspalum vaginatum by spikelet shape and by the longer, apiculate fertile floret.