3. Ptilagrostis dichotoma Keng ex Tzvelev, Rast. Tsentr. Azii. 4: 43. 1968.
双叉细柄茅 shuang cha xi bing mao
Perennial, densely tufted. Culms 15–50 cm tall, 0.7–1 mm in diam., 1–2-noded. Leaf blades setaceous, up to 20 cm, abaxial surface smooth or scabrid; ligule triangular or lanceolate, 1–3 mm. Panicle open, ovate in outline, 6–10(–14) × 2–6 cm; branches usually single, rarely paired, dichotomously branched, sometimes with prominent axillary cushions, filiform, bare in lower part; pedicels slender, 5–15 mm. Spikelets purplish or gray-brown, whitish at apex; glumes elliptic, 4.5–6.5 mm, 3-veined, apex usually smooth, obtuse to acute; lemma 3.6–5.2 mm, pilose below middle, scabrid or minutely pubescent above; awn 1–2 cm, column twisted, plumose, hairs 1.2–3 mm below bend, shorter above; palea equal to lemma, 2-veined. Anthers 1–2 mm, bearded at apex. Fl. and fr. Jul–Sep.
Alpine meadows, grassy mountain slopes, forests, under shrubs; 3000–4800 m. Gansu, Nei Mongol, Qinghai, Shaanxi, Sichuan, Xizang, Yunnan [Bhutan, N India, Nepal].
Specimens from the southern slope of the Himalayas usually have smooth leaf blades, but those from further north generally have scabrid blades. An exceptionally tall specimen with small spikelets (3.2–4 mm) and very scabrid panicle branches, collected at 2800 m in Qinghai (Nanshan), has been separated as Ptilagrostis dichotoma var. roshevitsiana Tzvelev (Rast. Tsentr. Azii 4: 43. 1968). It seems likely that this will prove to be a different species when more material is available.
Ptilagrostis dichotoma is very indistinctly separable from P. mongholica, and specimens from the Himalayas have been identified as the latter. However, the presence of shorter, bearded anthers does seem to be correlated with a slightly different smaller habit and shorter awns. Ptilagrostis dichotoma is also very close to P. concinna, but it lacks the sheathing, membranous bract at the base of the panicle characteristic of that species.