Comet Grass

This species is probably the same as P. hordeiformis Nees which is characterized by its definite lines of hairs along the dorsal surface of the glumes.

This species is at the northern limit of its range in S China, and can be distinguished by its much more loosely arranged inflorescence of very narrow spikelets, with the tips drawn out into longer awns.

Culm tufted. Blade lanceolate, about 3 cm long by 4 mm wide; ligule about 0.2 mm long, minutely ciliate on upper margin. Inflorescence a single terminal raceme, about 9-10 cm long. Spikelets 1-flowered, 3.5-4 mm long; glumes lanceolate, hispid on backside, tipped with a long awn, 1-nerved; the lower glume about 3.5 mm long, excluding the long awns which are about 25 mm long; the upper glume of nearly the same length as the lower, tipped with a long awn of about 18 mm long; lemma lanceolate, hyaline, 1-nerved, acute, about 1.2 mm long; palea hyaline, 2-nerved, about 0.8 mm long, minutely ciliate at the apex. Caryopsis about 2 mm long; embryo 1/3 the length of the caryopsis.

Annual or short-lived perennial. Culms loosely tufted, decumbent at base, 15–40 cm tall. Leaf sheaths glabrous; leaf blades lanceolate to narrowly ovate, flat or margins involute, tough, 1.5–5 cm, 2–5 mm wide, glaucous, glabrous, margins spiny-scabrous, pectinate at base, apex acute. Inflorescence up to 20 cm; spikelets laxly arranged, horizontally spreading, lightly reflexed at maturity; rachis scaberulous-hirtellous. Spikelets 3.5–4.5 mm (excluding awns); basal callus 0.5–1.5 mm, narrowly obconical, flattened, sometimes laterally pubescent; glumes linear-lanceolate, back evenly scaberulous-hirtellous with short white hairs, midvein scabrous with longer prickles toward awn, apex gradually tapering into awn; awn 1–2.5 cm; lemma 1.2–1.5 mm. Anthers ca. 0.6 mm. Caryopsis terete, subulate, ca. 2.5 mm. Fl. and fr. Jun–Nov.

Sandy seashores. Fujian, Guangdong, Guangxi, Hainan, Taiwan [New Guinea, Philippines, Thailand, Vietnam; Australia].

Perotis macrantha Honda, Bot. Mag. Tokyo 41: 638. 1927; Taiwan Grass. 435. pl. 113. 1975; Hsu, Fl. Taiwan 5: 496. 1978.

Diplachyrium rarum (R. Brown) Nees; Perotis longiflora Nees; P. macrantha Honda; P. patula Nees; Saccharum rarum (R. Brown) Poiret.

Perotis rara is a species of grass in the family, Poaceae, first described by Robert Brown in 1810. It is native to Australia, South-east China, Malaya, New Guinea, the Philippines, Taiwan, Thailand, and Vietnam.