4. Pennisetum purpureum Schumacher, Beskr. Guin. Pl. 44. 1827.
象草 xiang cao
Gymnotrix nitens Andersson; Pennisetum benthamii Steudel; P. flexispica K. Schumann; P. hainanense H. R. Zhao & A. T. Liu; P. macrostachyum Bentham (1849), not (Brongniart) Trinius (1834); P. nitens (Andersson) Hackel.
Perennial forming large tussocks, often with short rhizomes. Culms robust, decumbent and rooting at the base, ascending to 2–4 m tall. Leaf sheaths glabrous or hispid; leaf blades linear, up to 120 × 5 cm, abaxial surface glabrous, adaxial surface hispid or papillose-pilose at base, midrib prominent, margins scabrous; ligule 1.5–5 mm. Inflorescence linear, 10–30 × 1–3 cm, golden, brownish or purplish; axis densely pilose, closely beset with small peduncle stumps; involucre comprising many slender bristles, enclosing 1–5 spikelets, terminal spikelet fertile, subsessile, laterals when present staminate with 1–2 mm pedicels; inner bristles thinly plumose, longest 1–4 cm. Spikelets 5–7 mm; lower glume vestigial or absent; upper glume 1/4–1/2 as long as spikelet, acute; lower floret staminate or neuter, lemma 1/2–3/4 spikelet length, 5–7-veined, minutely hispidulous, acuminate; upper lemma membranous and obviously 5-veined toward narrowly acuminate tip, lower half cartilaginous, smooth and shiny; anthers with a tuft of short hairs at tip. Fl. and fr. Aug–Oct. 2n = 27, 28.
Cultivated. Fujian, Guangdong, Guangxi, Hainan, Jiangsu, Jiangxi, Sichuan, Taiwan, Yunnan [native to Africa].
This is an excellent forage grass, native in Africa, but now introduced to many tropical countries (Elephant Grass, Napier Grass).