3. Colpodium wallichii (Stapf) Bor, Kew Bull. . 1953: 270. 1953.
瓦小沿沟草 wa xiao yan gou cao
Catabrosa wallichii Stapf in J. D. Hooker, Fl. Brit. India 7: 312. 1896 ["1897"]; Paracolpodium wallichii (Stapf) E. B. Alexeev.
Perennial, shortly rhizomatous. Culms erect, 7–25 cm tall, 2–3-noded. Leaf sheaths longer than internodes; leaf blades narrowly linear to filiform, up to 10 cm × 1–2 mm, glabrous; ligule 2–2.5 mm. Inflorescence delicate, open, few-spiculate, almost racemose, 2.5–5.5 cm; branches 1 or 2 per node, up to 1 cm, capillary, flexuous, mostly bearing only 1 spikelet, occasionally 2, equaling or longer than spikelet, gently reflexing at maturity. Spikelets 3.7–5.5 mm, floret 1, purple or less often greenish; glumes slightly shorter to slightly longer than floret, lower glume narrowly lanceolate, 3–5 mm, apex subacute, upper glume lanceolate-oblong,3.5–5.5 mm, apex narrowly obtuse; lemma narrowly lanceolate-oblong, 3.2–4.3 mm, obscurely 3–5-veined, shortly pubescent along veins below middle, sometimes a few hairs on lower back, apex obtuse to truncate-denticulate; palea keels shortly pubescent; rachilla extension present, short. Stamens 2; anthers 2–2.5 mm.
Stony or sandy places in trickling water from snow melt; above 4000 m. ?Xizang [Bhutan, India (Sikkim), Nepal].
This species is very likely to occur in the mountains of S Xizang, but the illustration in Fl. Xizang. (5: 141. 1987, as Catabrosa wallichii) appears to be a form of Catabrosa aquatica.