4. Trisetum clarkei (J. D. Hooker) R. R. Stewart, Brittonia. 5: 431. 1945.
长穗三毛草 chang sui san mao cao
Avena clarkei J. D. Hooker, Fl. Brit. India 7: 278. 1896 ["1897"].
Perennial, loosely tufted. Culms erect from ascending base, (30–)50–70 cm tall, 0.5–1 mm in diam., pubescent especially below panicle, 1–3-noded. Leaf sheaths pubescent; leaf blades flat, 5–20 cm, 1.5–2(–4) mm wide, pubescent or scaberulous; ligule 1–2 mm. Panicle contracted, linear to lanceolate in outline, usually slightly loose, at least lower branches obvious, 5–18 cm, brown, green, or yellowish green; branches slender, erect or slightly spreading, pubescent. Spikelets 4–8.5 mm, florets 2 or 3; rachilla hairs ca. 1.5 mm; glumes unequal, narrowly lanceolate, lower glume 4–6 mm, upper glume 5–7.5 mm, apex sharply acute; lemmas narrowly lanceolate, 3.5–7 mm, scabrid, awned from near upper 1/3, apex usually 2-denticulate, teeth mucronate, occasionally subentire; awn strongly recurved at base, 4–8 mm, fine, not twisted; palea keels scabrid. Anthers 1.3–1.6 mm. Fl. Jul–Sep.
Montane forests, among bushes, moist grassy mountainsides; 1900–4300 m. Gansu, Hubei, Qinghai, Shaanxi, Sichuan, Xinjiang, Xizang, Yunnan [E Afghanistan, NW India, Kashmir, Pakistan].
The boundary between Trisetum spicatum and T. clarkei is obscured by intermediates, which are probably the result of introgression between the two species. Trisetum clarkei tends to be a taller, more slender grass, with a slightly looser panicle of narrower spikelets with well-exserted awns.