Green Bristlegrass

Setaria viridis, Green Bristle Grass, is extremely close to the cultivated Setaria italica. differing mainly in the manner in which the spikelet breaks up. In Setaria viridis, as in other species of Setaria, the spikelet falls entire from the pedicel, but in Setaria italica the glumes and lower lemma persist while only the upper floret is shed.

Annuals; clum glabrous, geniculate, 40-80 cm tall. Blade broadly linear, 5-20 cm long, 2-18 mm wide; sheath ciliate on margins; ligule a ring of hairs, ca. 1.5 mm long. Panicle contracted, spike-like, cylindrical, 3-6 cm long; axils pubescent; sterile branches forming bristles subtending spikelet. Spikelets 2-2.5 mm long, 0.8-1 mm wide; elliptic, usually obtuse; lower glume 3-veined, ovate, ca. 1/3 as long as spikelet; upper glume 5-veined, equaling spikelet or shorter; lower lemma 5-veined, enclosing a small, narrow, lower palea; upper lemma oblong, obtuse, obscurely rugose, finely punctate. Anthers ca.0.7 mm long.

Annual. Culms tufted, erect or geniculate, up to 70(–150) cm tall, 3–7 mm in diam. Leaf sheaths glabrous to papillose-pilose, margins densely ciliate; leaf blades linear to linear-lanceolate, flat, glabrous or papillose-pilose on both surfaces, base subrounded or subtruncate, margins scabrous, apex acuminate; ligule 1–2 mm. Panicle dense, usually cylindrical, usually tapering upward, 1–24 cm, erect or slightly nodding, branchlets bearing several spikelets each subtended by 3–7(–25) bristles; axis pilose or pubescent; bristles green, brown or purple, 4–12 mm. Spikelets elliptic-oblong, 2–2.5(–3) mm, obtuse; lower glume 1/4–1/3 as long as spikelet, obtuse or rarely acute; upper glume elliptic, as long as spikelet, lower lemma equal to spikelet; lower palea about 1/3 as long as lemma; upper lemma pale green, oblong, finely punctate-rugose, obtuse. Fl. and fr. May–Oct. 2n = 18.

Loosely tufted annual; culms 10-50 cm high, erect or geniculately ascending. Leaf-blades broadly linear to narrowly lanceolate, 5-20 cm long, 4-12(18) mm wide, rounded at the base, flaccid, smooth or scaberulous; sheaths glabrous to pubescent, sometimes with tubercle-based hairs. Panicle spiciform, linear or sometimes ± lobed below, 2-12 cm long, the rhachis puberulous to hispidulous; bristles 3-12 mm long, antrorsely scabrid. Spikelets ellipsoid, 2-2.5(3) mm long; lower glume a quarter to a third the length of the spikelet; upper glume as long as the spikelet; lower floret barren, its plea about half as long as the lemma; upper lemma finely rugose.

Cooler parts of Old World, introduced in New World.

Widely distributed in the Old World. Taiwan, in sandy seahsores.

Distribution: Pakistan (Baluchistan, Punjab, N.W.F.P., Gilgit & Kashmir); in the cooler regions of the Old World; introduced to the New World where it has escaped and is considered a weed.

2300-3800 m

Fl & Fr. Per.: June-September.

Hill slopes, roadsides, grassy waste places. Anhui, Fujian, Gansu, Guangdong, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [temperate and subtropical regions of the Old World; introduced elsewhere].

Panicum viride L., Syst. Nat. ed. 10. 2: 870. 1759. Panicum pachystachys Franch & Sav., Enum. Pl. Jap. 2: 161. 1876. Setaria viridis (L.) P. Beauv. var. pachystachys (Franch. & Sav.) Makino & Nemoto, Fl. Jap. 1499. 1925; Hsu, Fl. Taiwan 5: 608. 1978.