1. Themeda triandra Forsskål, Fl. Aegypt.-Arab. 178. 1775.
黄背草 huang bei cao
Anthistiria japonica Willdenow; Themeda barbinodis B. S. Sun & S. Wang; T. japonica (Willdenow) Tanaka; T. tri-andra var. japonica (Willdenow) Makino.
Perennial from a knotty rootstock. Culms tussocky, yellowish, usually farinose near nodes, 0.5–1.5 m tall. Leaf sheaths usually hispid with tubercle-based hairs; leaf blades 10–50 × 0.4–0.8 cm, glabrous or pilose, finely acuminate; ligule 1–2 mm, truncate, ciliate. Compound panicle lax, open, with spaced, often nodding spathate fascicles; spathes and spatheoles narrowly lanceolate, glabrous or thinly to densely tuberculate-hispid, innermost 2–3.5 cm. Raceme composed of a triad of 1 sessile and 2 pedicelled spikelets above the involucre of 2 homogamous pairs. Homogamous spikelets all sessile, arising at same level, staminate, both glumes present, 7–14 mm, oblong-lanceolate with lateral scarious wings, glabrous or hispid with tubercle-based hairs. Sessile spikelet 5–7 mm; callus 1.5–3 mm, pungent, brown bearded; lower glume dorsally rounded, dark brown, glossy, hispidulous in upper 1/3, smooth below; awn 3.7–7 cm. Pedicelled spikelet 7–12 mm, male or barren. Fl. and fr. Jun–Dec. 2n = 20, 40, 50, 60, 70, 80.
Dry mountain slopes, roadsides, forest margins; 100–3000 m. Anhui, Fujian, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [Bhutan, India, Indonesia, Japan, Korea, Malaysia, Myanmar, Nepal, Philippines, Sri Lanka, Thailand, Vietnam; Africa, SW Asia, Australia].
This is a highly polymorphic, predominantly apomictic species with a wide range of chromosome numbers.
The name Themeda arguens (Linnaeus) Hackel has been misapplied to this species in Yunnan. True T. arguens is not yet known from China. It occurs from Thailand and Vietnam to Australia, and can be distinguished by its reddish culms, very large, spathate fascicles with awns 7–9 cm, and longer callus 3–4 mm. It also differs from T. triandra by its glabrous leaf sheaths, blunter leaf blades, and homogamous spikelets consisting only of the lower glume.