|
CENCHRUS L. Sandbur
Plants caespitose, annual or perennial. Culms ascending or geniculate; internodes hollow or solid, terete.
Leaves not differentiated into two kinds (basal rosette absent), basal and cauline, not distinctly distichous;
sheaths terete or with compressed keels; ligules a ciliate membrane; blades flat or folded. Panicles
contracted (spicate) with spikelets borne in deciduous fascicles (burs), the burs in an involucre of
connate basally flattened bristles that represent modifid panicle branches; disarticulation at base of burs;
primary branches terminating in a bristle; bristles of burs flattened, connate, retrosely hispid.
Spikelets solitary, partially embedded in branch, dorsiventrally compressed; florets 2; lower sterile
and staminate or without stamens; upper floret fertile, equal or longer than lower floret; first glumes
present or absent, not fused with callus, not encircling spikelet base, awnless; second glumes present,
0.3-1 times spikelet length, not saccate, 1-7-venied; lemmas of upper florets chartaceous, smooth or muricate,
yellow to green, glabrous to scabrous, margins flat, not differentiated at apex, awnless; paleas of upper
florets present. Stamens 3; anthers tan. Base chromosome number x=9 and maybe 12.
A genus of about 15 species that occur in tropical and subtropical regions of the world. Cenchrus is most
similar to Pennisetum. In Texas, the genera can be separated in that Cenchrus has retrorse barbs on the bristles
whereas in Pennisetum the bristles are antrorsely barbed.
|
