2. Heteropogon contortus (Linnaeus) P. Beauvois ex Roemer & Schultes, Syst. Veg. 2: 836. 1817.
黄茅 huang mao
Andropogon contortus Linnaeus, Sp. Pl. 2: 1045. 1753; Heteropogon fertilis B. S. Sun & S. Wang.
Perennial. Culms slender, tufted, usually geniculate at base, 20–100 cm tall. Leaf sheaths keeled; leaf blades flat or folded, 10–20 × 0.3–0.6 cm, scabrid or adaxial surface pilose at base, apex obtuse or shortly acute to apiculate; ligule ciliate along margin. Inflorescence terminal or racemes gathered into a scanty panicle; spatheoles linear, tightly rolled around peduncle; peduncles mostly long-exserted. Racemes 3–7 cm (excluding awns), narrowly cylindrical, 7–12-awned, (1–)3–10(–12) pairs of flat green homogamous spikelets below the awned fertile pairs. Sessile spikelet 5–7 mm, dark brown; callus 2–3 mm, fiercely pungent, brown bearded; lower glume linear becoming cylindrical at maturity, sometimes hispidulous between veins; awn 6–10 cm, dark brown, column white-hirtellous, tips of successive awns often twisting together. Pedicelled spikelet 6–11 mm, lower glume oblong-lanceolate, greenish, laterally asymmetrically winged, glabrous or sparsely to densely pilose or tuberculate-hispid or white setose. Fl. and fr. Apr–Dec. 2n = 20, 40, 44, 50, 60, 80.
Dry hillsides, roadsides, grassy places, in the open or light shade; 400–4500 m. Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [tropics and subtropics of the world, extending to Mediterranean and other warm-temperate areas].
The narrowly cylindrical racemes of overlapping, green spikelets with stout, brown, intertwining awns emerging from the upper part are very characteristic of this species. It is a very widespread and extremely polymorphic species, varying in habit, hairiness of the spikelets, and also physiologically in response to differing rainfall regimes. It is apomictic and includes a range of chromosome numbers. The name Heteropogon fertilis has been applied to an atypical, stunted specimen lacking homogamous spikelet pairs at the base of the raceme. It was described from Yunnan, but similar forms with only a single homogamous spikelet pair are known from Hong Kong and elsewhere.
This species provides good forage when young, but the needle-sharp spikelet calluses can cause damage to livestock when mature. The leaves and stems are utilized in papermaking.