32 



POACEAE 



Callus of the lemma glabrous. 



Second empty glume similar to the first one or nearly so. 



Panicle narrow, dense and spike-like, sliining; its branches erect- 



56. KOELERIA. 



Panicle open; its branches spreading. 



Rachilla continuous (except in E. megasiachya); lemma decidu- 

 ous; palet persistent; plants of dry soil. 



57. Eragrostis. 



Rachilla articulated; lemma and palet both deciduous with 

 the rachilla-internodes; water plants with 2-flowered 

 spikelets, 58. Catabrosa. 



Second empty glume very unlike the first one, broad at the summit. 



59. SPHEXOPHOTJ9. 



Lemma 5-many-nerved. 



Spikelets with two or more of the upper glumes empty, broad and enfold- 



int? each other. 60. Melica. 



Spikelets with upper glum.es flower -bearing or narrow and abortive. 

 Stigmas arising at or near the apex of the ovary- 



Spikelets borne in one-sided fascicles which are arranged in a glom- 

 erate or interrupted panicle; lemma herbaceous. 



61. Dactylis. 

 Spikelets borne in panicles or racemes. 



Glumes more or less compressed and keeled. 



Spikelets cordate, large. 62. Briza, 



Spikelets not cordate. 



Plants dioecious; lemma of the pistillate spikelets cori- 

 aceous; palet strongly 2-keeled and serrate on the 

 margin. 63. Distichws. 



Plants with perfect flowers or in some species of Poa dioe- 

 cious; spikelets all alike; lemma thin; palet ciliate 

 or smooth on the margin. 

 Lemma scarious-margined; rachis glabrous or with 



webby hairs. 64. PoA. 



Lemma membranoiis, not scarious-margined; rachis 

 with stiff hairs, extending into a hairy appendage. 



35. GRAPnEPHOi{r\f. 



Glumes rounded on the back, at least below. 



Lemma with a basal ring of hairs, prominently 7-nerved, 



toothed at the apex. 65. Scolochloa. 



I-emma naked at the base. 



Lemma obtuse or acutish and scarious at apcx» usually 



toothed. 

 Lemma distinctly 5-7-nerved; style present. 



06. PaxicULARIA. 



Lemma obscurely 5-nerved; style none. 



67. PUCCINELLIA. 



Lemma acute, pointed or more commonly awned at ape.x* 

 Stigmas bilaterally plumose; flowers hermaphrodite. 



68. FESTUCA. 



Stigmas subplximose, the branches arising on all sides; 

 plant dioecious. 69. HESPEROCHliOA. 



Stigmas plainly arising below the apex of the ovary which is tipped by 

 a hairy cushion, 70. Bromus. 



Tribe 10. HORDEAE. 



kelets usually single at the nodes of the rachis. 



Empty glumes broad, with their sides turned to the rachis. 



Glumes broad, several-toothed or several-awned. 73. Trtticum. 

 Glumes not toothed, 1-awned or awnless. 



Perennials; spikelets several-flowered. 72. Agropyron, 



Annuals or biennials; spikelets 2-flowered. 74. Secale. 



Empty glumes with their back turned to the rachis. 71. Loulm. 

 kelets 2-6 at each node of the rachis, or if solitary the empty glumes arranged oblicjuely 

 to the rachis. 



Spikelets 1-flowered or with a rudimentary second flower. 75. HORDEUM. 

 Spikelets 2-many-flowered. 



Rachis of spikes articulated, readily breaking up into joints 

 Rachis of spikes continuoas, not breaking up into joints. 

 Empty glumes well developed. 

 Empty glumes wanting or reduced to short bristles. 



SiTANJON. 



77. ELYMUS. 



78. HViSTUIX. 



1. SCHIZACHtRIUM Nees. Bkard-grass, Bunch-grass. 



Annual or perennial grasses, with spike-like racemes, singly disposed, tenain- 



ating the stem or its branches. Spikelets in pairs at the nodes of the articulate 



and frequently hair>^ rachis, one sessile, the other stalked. Sessile spikelet of 4 



glumes, the outer 2 empty glumes indurate, the third and the lemma hyaline; 



the latter bearing a straight, contorted, or twisted awn; palet small, hyaline. 



Pedicellate spikelet sterile, with 1 or 2 glumes, or rarely wanting. Stigmas 

 plumose. 



