166. Urochloa P. Beauvois, Ess. Agrostogr. 52. 1812.
尾稃草属 wei fu cao shu
Authors: Shou-liang Chen & Sylvia M. Phillips
Annuals or perennials, often coarse and weedy. Leaf blades linear to broadly lanceolate; ligule a ciliate membrane. Inflorescence composed of racemes along a central axis; spikelets single or paired on a flattened or triquetrous rachis. Spikelets lanceolate or elliptic, plano-convex, cuspidate to acuminate, florets 2; lower glume abaxial, variable in length; upper glume and lower lemma similar, as long as spikelet, membranous to firmly papery; upper lemma coriaceous, rugulose or granular, margins inrolled, shorter than spikelet with a slender mucro lying within the cuspidate spikelet tip. x = 7, 10, 16.
Twelve species: tropics of the Old World; four species in China.
Urochloa is closely related to Brachiaria, and the two are united by some authors. They are distinguished mainly by habit, Urochloa having rather more flattened, cuspidate spikelets enclosing a pronounced mucro from the upper lemma. The different spikelet orientation is also characteristic, though not obvious when the spikelets are paired. In Urochloa the lower glume faces outward, whereas in Brachiaria it lies against the rachis.
