512 CONTRIBUTIONS FROM THE NATIONAL HERBAEIUM. 



^^^\ Panicum trigonum Retz.,' an East Indian perennial with low creeping and 

 branching culms and spreading pilose blades 2 to 4 cm. long, contracted panicles of 

 short-pediceled hispidulous epikelcts about 1.7 mm. long, the second glume keeled, 

 the fruit slightly compressed laterally, has been found "under the shade of a shrub," 

 Port of Spain, Trinidad, Broadway 4891. / (^cyt^Ai:;><ic^<-<t.-H^ 7^i^.^W^>i-«<''W»-^ ^-^^ 



Subgenus DICHANTHELIUM Hitchc. & Chase. '''^J^^c^*-.-*^ ' 



Foliage soft and lax, the flat blades prominently ciliate; ^^^'"^"^ /^^a 



plants branching from the base, finally forming ro- ^ 



settes or cushions See Laxiflora, p. 513. 



Foliage not soft and lax; plants branching from the culm 

 nodes. 



First glume nearly as long as the spikelet See Coedovensia, p. 525. / 



First glume much shorter than the spikelet. 



Spikelets glabrous; plants glabrous throughout; 

 ^: , autumnal form erect, not bushy-branching. See Dichotoma, p. 516. 



Spikelets pubescent. 



Sheaths glabrous or minutely puberulent 

 onlf ; ligules minute or obsolete. 

 Spikelets attenuate at base, mostly 

 prominently pustulose; blades 

 narrow, stiff, strongly nerved, ta- 

 pering from base to apex See Angustifolia, p. 514. 



Spikelets not attenuate at base, not pus- 

 tulose. 

 Spikelets subglobose or pyiiform. 

 Blades spreading, rarelj^ over 5 

 cm. long and 5 mm. 

 wide, spikelets pyiiform; 

 autumnal form bushy- 



brancliing See Lancearia, p. 522. 



Blades erect, 7 to 13 cm. long, 

 7 to 14 mm. wide; spike- 

 lets spheroid See Sphaerocarpa, p. 521. , 



Spikelets not subglobose nor pyri- 

 ^ form. 



Spikelets 2.8 mm. or more long. See Commutata, p. 524. 

 Spikelets not OA^er 2 mm. long. 

 Blades with a cartilaginous 

 white margin; spike- 

 lets not over 1.5 mm. 



long 101. P. alboviarginatum. 



Blades not white-margined; 



spikelets 2 mm. long. See Dichotoma, p. 516. 

 Sheaths pubescent. 



Spikelets 4 mm. long, pyiiform 104. P. nodatuvi. 



Spikelets not over 2.6 mm. long. 



Spikelets attenuate at base, mostly 

 prominently pustulose ; blades 

 naiTow, stiff, strongly nerved, 

 tapering from base to apex; 

 autumnal form often bushy- 

 branched See Angustifolia, p. 514. 



iQbs. Bot. 3:9. 1783. 



