[Pennisetum cenchroides (L.) Rich.; P. ciliare (L.) Link]
(nat) Buffelgrass
Perennials, sometimes short-rhizomatous and forming mats or tussocks; culms ascending, 10-150 cm tall, 1-2 mm in diameter, wiry or sometimes almost woody at base, sometimes many-branched from lower or basal nodes. Sheaths keeled, glabrous or sparsely pilose; ligule a densely ciliate membrane 0.5-2.5 mm long; blades 3-25 cm long, 2-13 mm wide, glabrous or sparsely pilose, apex caudate. Inflorescences paniculate, gray, purple, or yellowish, densely cylindrical to ovoid, 2-14 cm long, 1-2.6 cm wide, rachis angular and puberulent; burs 6-16 mm long, bristles connate only at base to form a disk 0.5-1.5 mm in diameter, inner bristles much exceeding spikelets, 1 of them longer and stouter than the rest, at least the longest somewhat flattened at base, sparsely or densely ciliate below, grooved on the face or not, filiform above, flexuous, often wavy, antrorsely scaberulous, outer bristles filiform; spikelets 1-4 per bur, 2-5.5 mm long, dorsally compressed, lanceoloid; glumes distinct, first glume membranous, 1-nerved, 1-3 mm long, second glume 1-3-nerved, 1.3-3.5 mm long; first lemma 5-6-nerved, 2.5-5 mm long; palea 2.5-5 mm long, enclosing a staminate flower; second lemma thin, 5- nerved, 2.2-5.4 mm long. Caryopsis turgid, ovoid, 1.4-1.9 mm long, ca. 1 mm in diameter. [2n = 32, 34, 35, 36, 40, 43-45, 48, 52, 54, 56.] Native to Africa and tropical Asia, naturalized elsewhere in the Old World; in Hawai‘i naturalized and common in dry areas and sandy soil in a wide variety of disturbed habitats, 0-120 m, on all of the main islands except Ni'ihau. First collected on Hawai‘i in 1932 (Ewart III258, BISH).
This species is very similar to species of Pennisetum. The bristles of the involucre in Cenchrus are connate, while those in Pennisetum are distinct. Cenchrus ciliaris has the least connate involucral bristles in the genus and thus has been alternately placed in both genera.