Trisetum clarkei (Hook. fil.) R. R. Stewart

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.

Trisetum clarkei and Trisetum spicatum can, at times, be very difficult to distinguish. Their obvious differences, clearly seen when good specimens are placed side by side, preclude the possibility that they are only subspecies or conspecific. There are no substantial quantitative differences except that in Trisetum clarkei the glumes and lemmas are slightly narrower than in Trisetum spicatum, a feature that correlates well with the looseness of the panicle. It is possible that the boundary between the two is obscured by hybridisation.

Trisetum clarkei is common in alpine pastures from 2700 to 4000 m.

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.

Tufted perennial; culms 20-70 cm high, erect or geniculately ascending, puberulous especially below the inflorescence. Leaf-blades 4-20 cm long, 1.5-2(-4) mm wide, flat, pubescent to scaberulous. Panicle lanceolate to subcylindrical, loose or sometimes ± dense, the axis and branches puberulous, 4.5-18 cm long, 1-3 cm wide. Spikelets 2-3-flowered, 5-8.5 mm long excluding the awns; glumes unequal, lanceolate, acute, the lower 3-nerved, 4-6 mm long, the upper (4.5-)5.5-7.5 mm long; lemma narrowly elliptic, (5.2-)5.5-7mm long; awn 4-8 mm long, strongly recurved.

Himataya (Kashmir to Nepal).

Gansu, Hubei, Qinghai, Shaanxi, Sichuan, Xinjiang, Xizang, Yunnan [E Afghanistan, NW India, Kashmir, Pakistan].

Distribution: Pakistan (N.W.F.P. & Kashmir); Nepal and Northwest India.

3500 m

Fl. & Fr. Per.: July-September.

Montane forests, among bushes, moist grassy mountainsides; 1900–4300 m.

Avena clarkei J. D. Hooker, Fl. Brit. India 7: 278. 1896 ["1897"].