4. Piptatherum laterale (Regel) Munro ex Nevski, Trudy Bot. Inst. Akad. Nauk SSSR, Ser. 1, Fl. Sist. Vyssh. Rast. 4: 217. 1937.
细弱落芒草 xi ruo luo mang cao
Milium laterale Regel, Trudy Imp. S.-Peterburgsk. Bot. Sada 7: 645. 1881; Oryzopsis lateralis (Regel) Stapf ex J. D. Hooker.
Perennial, densely tufted. Culms 25–60 cm tall, 2–3-noded. Leaf sheaths glabrous, usually shorter than internodes; leaf blades rolled, setaceous or narrowly linear when flat, 5–15(–25) cm, 1–3 mm wide, abaxial surface scaberulous, adaxial surface pubescent; ligule lanceolate, 2–5 mm. Panicle loosely contracted to linear, 5–20 cm; branches 1–3 per node, erect or ascending, longest not usually more than 3 cm. Spikelets yellowish green, apex usually purplish; glumes lanceolate, 6–8 mm, herbaceous, apex acuminate; callus glabrous; lemma narrowly lanceolate to almost linear, (3.3–)4–6.5 mm, densely pubescent with 0.2–0.4 mm hairs, apex entire, awned from apex; awn sometimes tardily deciduous, delicate, 2–4(–6) mm, straight at insertion. Anthers 2–3.5 mm, bearded at apex. Fl. and fr. Jun–Aug.
Stony mountain slopes, grassy hollows, Kobresia pygmaea turf; 1800–4700 m. Sichuan, Xizang [Afghanistan, Kashmir, Kyrgyzstan, Nepal, N Pakistan, Tajikistan, Uzbekistan; SW Asia (Iran, Iraq, E Turkey)].
This is a variable species often confused in the literature with the closely related Piptatherum gracile.