陕西狼尾草 shan xi lang wei cao

Pennisetum longissimum var. intermedium S. L. Chen & Y. X. Jin.

Perennial forming loose tufts. Culms ascending from a shortly decumbent rooting base, 80–150 cm tall. Lower leaf sheaths papillose-pilose especially at mouth; leaf blades linear, thin, flaccid, 30–50 × 0.5–1.8 cm, subglabrous, smooth except for papillose-pilose base, margins scabrous; ligule ca. 2.5 mm. Inflorescence linear, 10–20 × 1.5–2 cm; axis densely hispidulous with angular ribs, peduncle stumps crowded, very short with a tuft of spiculae; involucre narrow, ascending, enclosing 1 spikelet; bristles purple, stiff, glabrous or inner thinly plumose in the lower part, unequal with one much longer than rest, longest 1.5–2.5 cm. Spikelet ovate-lanceolate, 5–6 mm; lower glume ovate, submembranous, ca. 2 mm, 1-veined or veinless, obtuse or erose; upper glume 1/3–1/2 as long as spikelet, 1–3-veined, acuminate; lower floret neuter, lemma as long as spikelet, 5–7-veined, palea small or absent; upper lemma 5–7-veined; anthers without hairs at tip. Fl. and fr. Jul–Nov.

* Mountain slopes, roadsides, field margins; 500–1100 m. Gansu, Hunan, Qinghai, Shaanxi, Sichuan, Yunnan.

This species is variable in the hairiness of the involucral bristles, which are never more than thinly hairy, and the hairs may be confined to the stout, longest bristle, or even absent altogether. The species can be recognized by its thin, flat leaves with papillose-pilose lower sheaths, hispidulous rachis, narrow involucres of stiff bristles, and empty lower lemma.