朗坦早熟禾 lang tan zao shu he

Perennials, with isolated shoots, rhizomes present, slender. Culms isolated or few together, 9–25 cm tall, 0.6–0.8 mm in diam., erect, smooth, with 2 or 3 nodes above base, none or 1 exserted, and several short leaves at the base. Leaf sheaths smooth, glabrous, 3.5–5 cm, 1.5–2 × as long as blade, uppermost closed for just over 1/2 of length, lowermost soon withering, becoming fibrous, not persisting; blades flat or folded, thin, 1.5–5 cm × 1–1.5(–2) mm, surfaces and margins smooth, of tillers few, short; ligule 0.5–1 mm, abaxially smooth, glabrous, apex truncate to obtuse, smooth, collars smooth, glabrous. Panicle open, 3–5 × to 3 cm, longest internodes 1–2 cm; branches spreading, flexuous, (1 or)2 per node, capillary, smooth (hooks very rare), longest 1.5–2.5(–3) cm with 3–4 spikelets in distal 1/2. Spikelets narrowly lanceolate, green or purple tinged, 3–3.5 mm, 2–3 × longer than broad, florets 2; vivipary absent; rachilla smooth, glabrous; glumes green, narrow, keel weak, veins inconspicuous, surfaces smooth, very thinly papery, minutely punctate-papillate, lower glume 1.5–2.2 mm, 1(or 3)-veined, keel smooth or sparsely scabrid, upper glume 2–2.7 mm, broader (to 0.6 mm), 3-veined, keel minutely scabrid; lemmas oblong, slightly arched along the keel, very thinly papery, 2.5–3.3 mm, apex acute, with a narrow bronze band below the narrow whitish tip, keel and marginal veins proximally pilulose to short villous, intermediate veins faint, area between veins glabrous (not minutely bumpy), distally smooth to sparsely scabrid; callus webbed with hairs to 1/2 as long as lemma on the lowest floret; palea smooth, glabrous between keels, keels finely scabrid, 3–16 hooks per keel. Anthers ca. 1.5 mm. Fl. and fr. Jun–Jul.

Grassy places in alpine river valleys; ca. 4000 m. ?Xizang [Nepal].

Poa langtangensis could be a weak form of P. pagophila from a cold, shady habitat. Unlike P. calliopsis, it has narrow spikelets that are not so clustered and deflexed. Although we have not found a voucher specimen for the record from Xizang, the type, from Nepal, is from within 10 km of the Xizang border.