4. Poa alpina Linnaeus, Sp. Pl. 1: 67. 1753.
高山早熟禾 gao shan zao shu he
Perennials, densely tufted; shoots intravaginal. Culms erect or obliquely ascending, (5–)10–30(–45) cm tall, usually several per tuft, smooth, nodes often 2, 1 exserted. Leaf sheath smooth, glabrous, 2 or more × as long as blade, basal ones persistent, investing culm bases, uppermost closed for 1/4 length; ligule white, 2–4(–5) mm, abaxially smooth, of tillers 1–2 cm long; blade grayish green, flat or folded, thickly papery, withering, 3–10(–16) cm, 2–6 mm wide, surfaces glabrous, margins smooth or sparsely scabrid, apex prow-tipped. Panicle loosely contracted to open, ovoid to oblong (pyramidal at anthesis), 2–7 × 2–3 cm, purple tinged; branches ascending to spreading, 2 per node, rounded, smooth or distally sparsely scabrid, longest 2(–3) cm, divaricately rebranched with moderately crowded spikelets in distal 1/2. Spikelets broadly ovate, 4–8 mm, florets 3–5(–7); vivipary absent in China; rachilla internodes ca. 0.5 mm, smooth, glabrous (rarely slightly pilulose); glumes broadly ovate, membranous-papery, subequal, faintly 3-veined, keel arched, scabrid, surfaces smooth, margins membranous, smooth, apex acute, lower glume 2.5–3(–4) mm, upper glume 3.4–4.5 mm; lemmas broadly ovate, membranous-papery, apex and margins broadly membranous, keel arched, keel villous for 2/3 of length, marginal veins for 1/2 length, intermediate veins indistinct, area between veins pilulose to short villous; callus glabrous; palea glabrous or proximally infrequently pilulose between keels, keels scabrid, often medially pilulose to shortly villous. Anthers 1.2–2 mm. Fl. and fr. Jul–Sep. 2n = 22, 28, 32, 33, 34, 35, 42, 44, 58.
Low arctic to subalpine meadows, sporadic in taiga, slopes, crevices along ditch banks, sandy places; 2400–3800 m. Qinghai, Xinjiang, Xizang [Afghanistan, India, Japan, Kazakhstan, Kyrgyzstan, Nepal, Pakistan, Russia, Tajikistan; SW Asia (Iran), Europe, North America].
This species has spikelets broadly ovate, lower glumes 3-veined, lemma proximally pubescent between veins, callus glabrous, old sheaths persistent and closely overlapping, anthers more than 1.2 mm, and palea keels shortly villous, together making it quite distinct from other species. Gatherings from arctic regions and European mountains are often viviparous, but such plants have not been recorded from China.