2. Poa tibetica Munro ex Stapf in J. D. Hooker, Fl. Brit. India. 7: 339. 1896 [“1897”].
西藏早熟禾 xi zang zao shu he
Poa chushualana Rajeshwari et al.; P. spiciformis D. F. Cui (2001), not (Steudel) Hauman & Parodi (1929).
Perennials, stoutly rhizomatous or stoloniferous; shoots mainly extravaginal. Culms erect or obliquely ascending (or geniculate), (15–)20–60(–90) cm tall, 2–3 mm in diam., smooth, glabrous, nodes 1 or 2 in lower part, sometimes 1 exserted, base enclosed in withered fibrous sheaths. Leaf sheaths of culm smooth, uppermost closed for 1/4–1/3 of length, of tillers smooth and glabrous or infrequently densely retrorsely scabrid to hispidulous; blade grayish green, flat, folded, or involute, papery, 3.5–12.5 cm, (1–)2–5 mm wide, abaxial surface smooth, adaxial surface with scabrid margins and veins, apex slender prow-tipped, somewhat pungent, blades of tillers 12–18(–35) cm, surfaces glabrous (or pubescent); ligule white or off-white, brownish to yellowish, firmly membranous, 1–2(–5.5) mm, abaxially scabrid, apex rounded, ciliolate, sometimes irregularly dentate. Panicle contracted to spikelike, often interrupted, 5–13 × 1–2(–3) cm; branches erect or steeply ascending, strict, (1–)2–4(–5) per node, rounded, smooth, longest 1–5 cm with spikelets from base or in distal 1/2–3/4. Spikelets pale green, sometimes purple, (4–)5–8(–9) mm, florets 3–6(–8); vivipary absent; rachilla internodes 0.5–1.5 mm, smooth or scabrid; glumes smooth except for a few hooks on the upper part of keel, margins smooth or faintly to prominently scabrid, proximally ciliate or villous, lower glume 2.5–4.6 mm, narrow, 1- or 3-veined, upper glume 3.5–6 mm, 3-veined; lemmas broadly lanceolate, 3.8–5.7 mm, apex and margins ± membranous, sometimes minutely mucronate, lower half of keel and marginal veins villous, upper part nearly smooth to closely scabrid, intermediate veins indistinct; callus glabrous or with 1 to several hairs, these straight, to 1.5 mm; palea smooth or scabrid between keels, keels ciliate, medially pilulose or villous, distally scabrid. Anthers 2–3.1 mm. Fl. and fr. Jul–Sep.
Marshy meadows, riversides, lake banks, grassy places, ditch banks, saline meadows, saline moist places; 3000–4500 m. Gansu, Nei Mongol, Qinghai, Xinjiang, Xizang [N India, Kashmir, Kazakhstan, Kyrgyzstan, Mongolia, Nepal, Pakistan, Russia (Siberia), Tajikistan; SW Asia (Iran)].
This is a stout species with well-developed, thick rhizomes, contracted to spikelike panicles, sparsely long villous lemma keel and margins, and usually a glabrous callus. The types of Poa chushualana, P. stenostachya, and P. spiciformis have not been seen, but their descriptions fit within the variation of this species, though they cannot all be placed to variety reliably. Poa chushualana, from Kashmir, just W of the Xizang border, is said to differ by its stoloniferous form, geniculate culm bases, and leaf blades 1–3 mm wide with pubescent surfaces. Poa tibetica s.l. needs detailed study. Some gatherings from China might be P. tianschanica. The exact identity of P. tianschanica is problematic and the Chinese material could prove to be a robust form of P. pratensis or the product of past hybridization with that species.