Description from Flora of China
Andropogon propinquus Kunth, Enum. Pl. 1: 502. 1833; A. halepensis (Linnaeus) Brotero var. propinquus (Kunth) Hackel; A. sorghum (Linnaeus) Brotero var. propinquus (Kunth) Hackel.
Perennial, loosely tufted with a few stout rhizomes. Culms 1.5–3 m tall, up to 1 cm in diam., many-noded; nodes puberulous. Leaf sheaths glabrous, ciliate at mouth and margins; leaf blades yellowish green, linear or linear-lanceolate, 40–90 × 3–5 cm, glabrous, midvein robust, margins ciliolate; ligule 0.5–1 mm, puberulous. Panicle open, ovate or broadly ovate, 30–55 cm; primary branches in whorls of 3–6; lower part bare, upper part branched, branches tipped by racemes; racemes fragile, composed of 3–7 spikelet pairs. Sessile spikelet ovate, 3.8–4.5 mm; callus obtuse, pubescent with pale hairs; lower glume subleathery, pale or purple-tinged, thinly pilose, 9–13-veined, veins distinct in upper part, apex acute to apiculate or tridenticulate; upper lemma acute or emarginate, awnless, rarely with short awn. Pedicelled spikelet staminate, linear-lanceolate, 4–5.5 mm, yellowish to pale purple. Fl. and fr. summer–autumn. 2n = 20.
This species is closely related to Sorghum halepense, but is diploid, is larger with a more profuse panicle, and has a different geographic distribution. It is sometimes used for fodder. A form with larger (4.5–5 mm) sessile spikelets, S. propinquum var. siamense (Piper) Snowden, occurs from S India to Thailand, but has not been found in China.
Streamsides, moist places. Fujian, Guangdong, Hainan, Sichuan, Taiwan, Yunnan (Funing, Hekou) [S India, Indonesia, Malaysia, Philippines, Sri Lanka].