1. Orinus thoroldii (Stapf ex Hemsley) Bor, Kew Bull. . 1951: 454. 1952.
固沙草 gu sha cao
Diplachne thoroldii Stapf ex Hemsley, J. Linn. Soc., Bot. 30: 121. 1894; Cleistogenes thoroldii (Stapf ex Hemsley) Roshevitz; Kengia thoroldii (Stapf ex Hemsley) H. Yu & N. X. Zhao; Orinus arenicola Hitchcock.
Rhizomes clothed in hard imbricate scales, roots woolly. Culms erect, slender, 12–20(–50) cm tall, smooth and glabrous or rarely loosely pilose. Leaf sheaths hirsute, densely so at mouth; leaf blades flat, finally involute, pale green, 2–9 × 0.2–0.5 cm, hirsute to subglabrous, base rounded, apex pungent; ligule lacerate, 1–1.5 mm. Panicle up to 15 cm, racemes 4–8, inserted singly, (1–)3–5(–7) cm, ascending or eventually spreading. Spikelets cuneate, 5–6.5(–11) mm, florets 2–5; rachilla glabrous, internodes 1–2.5 mm; glumes lanceolate, dorsally often purplish, margins hyaline, glabrous or loosely pilose; lower glume 3–5 mm; upper glume 4–6 mm; lemmas purplish brown to brown-black or blotched with purple, lowest 4.5–5(–7) mm, pilose all over, acute or mucronate; palea pilose along keels, between upper keels and on outer flaps, apex 2-lobed. Callus glabrous. Anthers (1–)3–3.5 mm. Caryopsis narrowly oblong. Fl. Aug.
High arid sandy or gravelly steppe, sometimes with Artemisia, fixed sand dunes; 3300–4300 m. Qinghai, Xinjiang, Xizang [Kashmir, Nepal].
The name Cleistogenes thoroldii has been misapplied to C. songo-rica in C Asian literature.