Part 3, 1915] 



POACEAE 



201 



above; pedicels and branchlets 

 irregularly arranged along the 

 main branches. 

 Plants decumbent and rooting at 

 the base, or producing stolons 

 (culm erect in P. cupreum); 

 panicle-branches forming dis- 

 tinct secund racemes, or naked 

 below with the spikelets aggre- 

 gated above (the lower branches 

 often compound). 

 Spikelets in open or sometimes in contracted 

 or congested panicles, but the main 

 branches not in narrow or spike-like 



First glume very small, not more than one- 

 fourth the length of the spikelet; 

 tropical species. 



Spikelets pointed; first glume obscure, 

 hyaline; leaf -blades long- tapering at 

 base. 



Spikelets obovate, blunt; first glume 

 membranaceous ; leaf -blades not taper- 

 ing at base. 

 First glume as much as one- third the length 

 of the spikelet; a few species with 

 pointed spikelets. 



Fruit silky- villous ; spikelets 6-7 mm. 

 long, densely villous; creeping rhi- 

 zomes present. 



Fruit glabrous. 



Panicle narrow and few-flowered; 



culms erect and wiry; leaf -blades 

 drying involute. 

 Panicle open or contracted, several - 

 to many-flowered. 

 Plants erect, not decumbent and 

 rooting at base (except P. 

 altum with culms 2-4: 

 meters tall). 

 Spikelets sparsely hispid. 

 Spikelets glabrous. 



Plants producing rhizomes 

 (except P. ichnanthoides) ; 

 mosstly tall, reed-like 

 gra ses. 

 Plant s without rhizomes; 

 c ulms less than 1 meter 

 tall (taller in P. hirsu- 

 t s um) ; leaf -sheaths hir- 

 s ute, at least in the taller 

 pecies. 

 Plants decumbent and rooting at 

 base, usually forming a 

 tangled mass (see also P. 

 altum) . 

 Spikelets viscid. 

 Spikelets not viscid. 



Leaf-blades very large, as 

 much as 1 meter long 

 and 6 cm, wide. 

 Leaf-blades not unusually 

 wide. 

 Panicle-branches, espe- 

 cially the lower, sev- 

 eral to many in dis- 

 tinct whorls, stiffly 

 ascending, naked be- 

 low. 

 Panicle-branches not in 

 consp icuous 

 whorls. 

 Fruit apiculate ; 

 spikelets of 2 

 kinds, more than 

 2.5 mm. long. 

 Fruit not apiculate ; 

 spikelets less 

 than 2.5 

 long. 



X. Agrostoidla. 



XI. Laxa. 



XLIV. TuERCKHElMlANA, 



XIII. Parviglumia. 



XVI. Urviu.eana, 



IX. Tenera. 



XXI. Rudgeana 



VIII. VlRGATA. 



VI. Diffusa, 



XX. GlyTJTlNOSA, 



XLII. Grandia. 



XXII. Megista. 



XL. CORDOVENSIA 



Mill 



