巴塘莠竹 ba tang you zhu

Basionym: Arthraxon batangensis S. L. Zhong, J. S. W. Agric. Coll. 1982(4): 97. 1982.

Perennial with tough, spreading rhizomes. Culms slender, much branched at lower nodes, sprawling, ascending to 20–45 cm, nodes glabrous. Leaf sheaths glabrous; leaf blades linear-lanceolate, firm, glaucous, 1–5.5 cm × 1.5–2 mm, smooth, abaxial surface glabrous, adaxial surface sparsely setose toward ligule with 2–3 mm bristles, apex acuminate; ligule 0.6–1 mm. Raceme solitary, 3.5–6.5 cm; rachis internodes filiform, ciliate with ca. 2 mm hairs, equaling spikelet. Sessile spikelets 6–7.8 mm; callus hairs 2–3 mm; lower glume linear-lanceolate, keels rounded in lower 2/3, sharp and scabrid above, deeply grooved between keels in middle 1/3, 5–7-veined with transverse veinlets, apex acuminate; upper glume with rounded keel, 7-veined with transverse veinlets, upper margins shortly ciliate, apex acute and mucronate; lower floret male with well-developed palea, anthers ca. 3 mm; upper lemma 3.5–4 mm, 2-lobed to below middle, lobes acuminate, ciliate on outer margins; awn geniculate, 1–1.4 cm; upper palea well developed. Pedicelled spikelet lanceolate, male and weakly awned or reduced and barren. Fl. and fr. Aug–Oct.

* Dry river valleys, under shrubs; 2600–3100 m. Sichuan.

This grass is not a species of Arthraxon because the awn arises from the sinus of the 2-lobed lemma, not from low down the lemma back. The habit, grooved lower glume of the sessile spikelet, and the usually well-developed pedicelled spikelet indicate that it is better placed in Microstegium.