2. Helictotrichon dahuricum (Komarov) Kitagawa, Rep. Inst. Sci. Res. Manchoukuo. 3: App. 1, 77. 1939.
大穗异燕麦 da sui yi yan mai
Avena planiculmis Schrader subsp. dahurica Komarov, Fl. Kamtschatka 1: 159. 1927; Avenastrum dahuricum (Komarov) Roshevitz; Avenula dahurica (Komarov) W. Sauer & H. Chmelistschek.
Perennial, rhizomatous, forming loose turf. Culms solitary or few, erect from decumbent base, 50–100 cm tall, 2–3-noded. Leaf sheaths of cauline leaves closed for 1/2 or more of length; leaf blades linear-lanceolate, flat, 8–25 cm, 5–12 mm wide, abaxial surface smooth with thick white midrib, adaxial surface scaberulous, margins thick, white, scaberulous, base rounded, apex abruptly acute; ligule lanceolate, 5–7(–10) mm. Panicle loosely contracted, 7–15 cm; branches usually paired, ascending, scabrid or almost smooth. Spikelets 1.7–2.5 cm, golden brown and purple, florets 5–6; rachilla hairs 1.5–2.5 mm; glumes membranous, 3-veined, lower glume 9.5–11 mm, upper glume 12–15 mm; lemmas leathery, hyaline above awn insertion, lowest 11–14 mm, asperulous, apex irregularly 2-denticulate; awn 1.5–1.7 cm, geniculate, column twisted, flat; palea keels ciliolate. Anthers 6.5–7 mm. Fl. and fr. Jul–Sep.
Open forests, grassy places, among shrubs; 700–1000 m. Heilongjiang, Nei Mongol [Mongolia, E Russia].
Helictotrichon dahuricum and H. hookeri belong to a group of species that have been shown by molecular studies to be only distantly related to Helictotrichon s.s. This group is sometimes separated as the genus Avenula. Some of the most obvious morphological distinctions are given in key couplet 2. Unfortunately the type species of Avenula is H. pubescens, which shows major morphological differences from the other species placed in Avenula, as noted above. For this reason Helicto-trichon is maintained here in the traditional sense. Further morphological and molecular studies are required to clarify relationships within the group.