77d. Poa versicolor subsp. reverdattoi (Roshevitz) Olonova & G. Zhu, Fl. China. 22: 305. 2006.
瑞沃达早熟禾 rui wo da zao shu he
Basionym: Poa reverdattoi Roshevitz in Komarov, Fl. URSS 2: 407. 1934; P. argunensis Roshevitz.
Culms densely tufted, (15–)35–45(–60) cm tall, erect, scabrid, sometimes tinged with grayish green, terminal node 1/6–1/3 way up culm. Leaf sheaths scabrid, shorter than internode, terminal sheath ca. 2 × as long as blade; blades folded or inrolled, hard, short, 0.5–1(–1.5) mm wide, abaxial surface and margin scabrid, adaxial surface minutely hairy; ligule (1–)2–2.5(–3) mm. Panicle contracted to spiciform, laxer at anthesis, 3–4 × (0.5–)1–5(–8) cm, branches 2 or 3 per node, with spikelets near base. Spikelets sometimes tinged with purple, 3–5(–6) mm, florets 2–4; rachilla glabrous or pilulose; glumes (2–)2.8–3(–3.5) mm; lemma keel shortly villous for 1/2 length, marginal veins for 1/3, area between veins minutely hairy for lower 1/3; callus usually moderately webbed to glabrous; palea minutely hairy in lower area between keels. Anthers ca. 2 mm. Fl. Jun. 2n = 28, 35, 42.
Dry grasslands on rocky slopes; 200–1000 m. Liaoning, Nei Mongol [Mongolia, Russia (S Siberia)].
This is a variable subspecies with a rather restricted distribution limited to low elevations of China, Mongolia, and S Siberia. Records of this subspecies from Xinjiang and the Altai region belong to Poa albertii.
Poa argunensis differs from subsp. reverdattoi only in variable and unreliable characters and forms many intermediate populations.