2. Tripogon humilis H. L. Yang, Acta Bot. Yunnan. 5: 72. 1983.
矮草沙蚕 ai cao sha can
Culms 5–8 cm tall. Basal leaf sheaths persistent in tight bunches; leaf blades setaceous, 1.5–6 × ca. 0.1 cm, adaxial surface densely hirtellous and thinly pilose, abaxial surface glabrous, sometimes scabrid. Racemes 2–4 cm, slender, rachis slightly laterally compressed, margins hirtellous, spikelets appressed to rachis, not or only slightly imbricate. Spikelets 3.5–5.5 mm, purplish brown; florets 2–4, imbricate; lower glume lanceolate, symmetrical, 2–3 mm, acuminate; upper glume lanceolate, 3–4 mm, apex acute-apiculate; lemmas oblong-ovate, 3–3.5 mm, 2-dentate, central awn 1.75–2.5 mm, erect, teeth broad, acute to truncate, lateral veins extended into 0.2–0.7 mm awns; palea keels ciliolate. Anthers 3, 0.5–0.8(–1.2) mm. Fl. Jul.
* Mountain slopes; ca. 2800 m. Xizang.
In the protologue, this small species was distinguished from Tri-pogon chinensis by its low stature and short racemes; it also has a rather longer central awn and short anthers. The type has not been seen. The awn length, anther length, and ciliolate palea keels of T. humilis exclude it from T. purpurascens.