[C. brevisetus Fourn.; C. echinatus var. hillebrandi- anus (Hitchc.) F. Brown; C. hillebrandianus Hitchc.; C. pungens Kunth]
(nat) Common sandbur, ‘ume'alu, mau ‘u kuku
Annuals; culms decumbent at base, 25- 70 cm tall, profusely branched, compressed, usually geniculate, often reddish at nodes and lower portion, usually scabrous for 3-4 cm below panicle, otherwise glabrous. Sheaths 4-7 cm long, glabrous or scaberulous, with a conspicuous whitish collar, compressed; ligule densely ciliate, ca. 1 mm long; blades flat, 5-18 cm long, 3-9 mm wide, striate, midrib conspicuous, upper surface scabrous and sometimes sparsely pilose at base, lower surface gla-brous or scabrous near apex. Inflorescences composed of racemes 3-7 cm long, rachis zigzag with scabrous angles; burs usually dark red to purple, readily deciduous, well-spaced, broadly ovoid, 4-7 mm long and as wide or wider, bur receptacle obconical, 1-2 mm long, tomentulose, lobes of bur deeply cleft, short-tomentulose, outer series of bristles 2-3 mm long, retrorsely scabrous, inner series of bristles rather flattened, short-pilose at base, retrorsely scabrous toward apex; spikelets 3-5 per bur, 4-6 mm long; first glume membranous, scale-like, indistinctly 1-nerved, 1-1.5 mm long, glabrous, second glume membranous, 4-4.5 mm long, prominently 3-nerved, minutely scaberulous, apex acute; sterile lemma 4.5-6mm long, 5-nerved, scaberulous, apex acuminate, sterile palea as long as sterile lemma, 2-nerved, submembranous, glabrous, apex attenuate; fertile lemma ca. 5 mm long, 5-nerved, nerves scaberulous near apex, apex attenuate; palea as long as lemma, 2-nerved, glabrous, apex acuminate. Caryopsis broadly ovate, usually flattened ventrally, rounded dorsally, 3-4 mm long. [2n = 34, 68.] Native to the Neotropics, now widely naturalized; in Hawai‘i naturalized in arid, disturbed habitats such as beach dunes, dry, rocky slopes, pastures, and along roadsides, 0-920 m, on Kure and Midway atolls, Lisianski, Laysan, French Frigate Shoals, Nihoa, and all of the main islands. First recorded from 0‘ahu in 1867 (Hillebrand, 1888).— Plate 222.