光花异燕麦 guang hua yi yan mai

Avena leiantha Keng, Bull. Fan Mem. Inst. Biol., Bot. 7: 35. 1936.

Perennial. Culms tufted, erect, up to 80 cm tall, 2–3-noded, glabrous or sparsely retrorsely pubescent below nodes. Leaf sheaths lax, glabrous; leaf blades flat or involute when dry, 10–30 cm, 3–6 mm wide, abaxial surface glabrous, adaxial surface pubescent, apex acuminate; ligule truncate, ca. 1 mm. Panicle loose, 15–18 cm, nodding; branches in distant pairs, slender, often flexuous, scabrid, lower ca. 7 cm, bearing up to 4 spikelets in upper part. Spikelets 1–1.3 cm, pale green, florets 3–4; rachilla internodes glabrous toward base, hairs in upper part 1–2 mm; lower glume 4.6–5 mm, 1-veined, upper glume 5–7 mm, 3-veined; lemmas subleathery with hyaline apex, lowest 9–10 mm, 7-veined, smooth, apex subentire, minutely denticulate; awn 1.5–2 cm, weakly geniculate, column loosely twisted, terete; palea keels ciliate, hairs ca. 0.3 mm. Anthers 3–3.5 mm. Fl. and fr. May–Jul.

* Under forests in high mountains, mountain valleys, shady mountain slopes, damp places; 700–3700 m. Anhui, Gansu, Guizhou, Hubei, Shaanxi, Shanxi, Sichuan, Yunnan, Zhejiang (Lin'an).

This is an element of the Helictotrichon junghuhnii complex with rather short rachilla hairs confined to the upper part of the rachilla internode, a more or less undivided lemma apex, and conspicuously ciliate palea keels. It is very similar to H. hideoi (Honda) Ohwi from Japan, which also has a subentire lemma apex, but differs by its pubescent leaf sheaths and awn arising slightly higher on the lemma back.