Ililchcock — The Grasses n( ITaivaii 109 



Spikelets witli (nily 1 pcvl'i'd llnrci, dficn with adilitioiial impiTl'cft Horets above. 



Rachilla iirolonged Init with 110 im])CTtci:t tlorcts 26. Capriola fp. 161 ) 



Rachilla hcariii.i,^ i or more mochficd llorcts aliovc the perfect one. 



Spikes (lii^itatc or nearly so 27. Chloris (p. 163) 



Spikes racemose alony tlie main axis 28. UoutiClou.v (p. 165) 



PHALARIDEAE. 



Glumes much shorter than the s])ikelet ^ 29. Micr()I,.\Kna (p. 167) 



Glumes not shorter than the spikelet. 



Lateral florets consisting of awiied liairy sterile lemmas exceeding (he fertile lloret ; spikelet 



terete 30. A nth o.x ant hum (p. 167) 



Lateral florets reduced to small awnless scalelike lemmas ; spikelets much compressed 

 laterally 31. Piialaris (p. 169) 



PANICEAE. 



Spikelets sunken in the cavities of the flattetied corky rachis 34. StkxoTai'IIRum (']i. 177) 



Spikelets not sunken in the rachis. 



Spikelets subtended or surrounded by I to many distinct or more or less connate bristles, 

 forming an involucre. 

 Bristles united into a burlike involucre, the bur falling entire. ...44. Cenchrus (p. 209) 

 Bristles not united, persistent, the spikelets deciduous. 



Lower floret sterile 42. Chaetochloa (p. 205) 



Lower floret fertile 43. Dissochondrus (p. 209) 



Spikelets not subtended by bristles. 



Glumes or sterile leniiua awned (awn short and concealed in the silky hairs of the 

 spikelet in Tricholaena, awn reduced to a point in Echinochloa colonuni). 



Inflorescence paniculate: spikelets silky 41. Tricholaena (p. 204) 



Inflorescence of unilateral simple or' somewhat compound racemes along a common 

 axis ; spikelets smooth or hispid, not silky. 

 Blades lanceolate, broad and thin : glumes 2-lobed. awned from between the 



lobes 39. Oi'LisMENus (p. 201 I 



Blades long and narrow; glumes awned from the tip 



40. Echinochloa (p. 202 ) 



Glumes and sterile lemma awnless. 



Fruit cartilaginous-indurate, flexible, usually dark C(.ilored, the lemma with luore or 

 less prominent white Inaline margins, these not inrolled. 



Spikelets covered with long silky hairs, arranged in racemes, these panicled 



32. V.\lota (p. 170) 



Spikelets glabrous or variously pubescent, but not long-silky, arranged in 



slender racemes, more or less digitate at the summit of the culms 



2^. Svntherisma (p. 170 ) 



Fruit chartaceous-indurate, rigid. 



Fertile florets 2 in each spikelet 38. Isachne (p. 201) 



Fertile floret i in each spikelet. 



First glume typically wanting (sometimes found in P. distich niii) ; spikelets 



plano-convex, subsessile in spikelike racemes 



35. Paspalum (p. 177) 



First glume present ; spikelets usually in panicles. 



Second glume inflated-saccate, this and the sterile lemma much exceed- 

 ing the stipitate fruit 37. SacciolEpis (p. 199) 



Second glume not inflated-saccate 36. Panicum (p. 181 ) 



ANDROPOGONEAE. 



Spikelets all perfect; inflorescence of 2 straight digitate racemes 43. IschaEmi'm (p. 213) 



Spikelets not all perfect, the sessile perfect, the pediceled staminate or rudimentary. 



Fertile spikelet with a hairy-pointed callus, formed of the attached supporting rachis joint 

 or pedicel. 



[II] 



