132 Gramineae 



12B. Spikelets 2- to many-flowered. 



1 9 A. Spikelets articulate above the glumes. 

 20A. Spikelets 2-flowered; lower floret staminate, the lemma long-awned from the back; upper floret perfect, the lemma 



awnless or nearly so 15. Arrhenatherum 



20B. Spikelets 2- to many-flowered; florets all perfect except the uppermost. 

 21 A. Lemmas awnless or awned from above the middle, acute or bifid at apex. 

 22A. Rachilla-joints long-hairy; lemmas awned. 



23A. Caryopsis sulcate, adhering to the lemma and palea; ovary hairy; spikelets usually more than 1 cm. long. 



24A. Annuals; spikelets pendulous; glumes 7- to 11-nerved, rounded at back, green 16. Avena 



24B. Perennials; spikelets erect; glumes slightly keeled, 1- to 3(-5)-nerved 17. Helictotrichon 



23B. Caryopsis not sulcate, free from the lemma and palea and enclosed by them; ovary glabrous (in ours); 



spikelets less than 1 cm. long; glumes 1- to 3-nerved 18. Trisetum 



22B. Rachilla-joints glabrous or short-pubescent; spikelets less than 1 cm. long, not awned (in ours) 19. Koeleria 



21B. Lemmas awned from the middle or above the base, truncate and erose at apex; spikelets less than 1 cm. long. 



20. Deschampsia 



19B. Spikelets articulate below the glumes; plant wholly velvety -hairy 21. Holcus 



IIB. Palea rounded or only obtusely angled at back; lemmas awned from apex or from between 2 minute teeth, or awnless; 

 lodicules 2, sometimes 3. 

 25A. Rather rigid grasses; spikelets lanceolate; lemmas awned between minute teeth. 



26A. Leaf-blades narrow; lemmas herbaceous; awns slender, slightly geniculate 22. Achnatherum 



26B. Leaf-blades flat, broader; lemmas coriaceous, with rather thick, almost straight, long awns 23. Orthoraphium 



23B. Soft grasses; spikelets ellipsoid, awnless 24. Milium 



lOB. Spikelet with the lower two florets staminate or neuter, sometimes reduced to minute scales; uppermost floret fertile. 



27A. Sterile florets scalelike, attached to the base of the bisexual floret; stamens 3 25. Phalaris 



27B. Sterile florets larger than the bisexual floret, brownish, hairy; stamens of the bisexual florets 2. 



28A. Sterile florets, at least the upper, neuter and epaleate 26. Anthoxanthum 



28B. Sterile florets all staminate, paleate 27. Hierochhe 



9B. Glumes equal or unequal, at least the lower shorter than the lowest lemma; awn of the lemma apical or nearly so, not genic- 

 ulate nor twisted, except in Tripogon. 

 29A. Lemmas 5- to many-nerved. 



30A. Inflorescence a spike; spikelets alternate on a flattened axis, sessile or nearly so; ligules very short, truncate, sometimes 

 auriculate. 

 31A. Spikelets all alike, 1- to many-flowered. 



32A. Spikelets solitary, rarely geminate at each node, not twisted. 



33A. Spikelets very short-pedicelled 28. Brachypodium 



33B. Spikelets sessile. 



34A. Spikelets placed flatwise to the rachis; both glumes developed 29. Agropyron 



34B. Spikelets placed edgewise to the rachis; first glume wanting except in the terminal spikelet 30. Lolium 



32B. Spikelets 2 or 3, rarely solitary at each node, somewhat twisted. 



35A. Glumes well developed 31. Elymits 



35B. Glumes wanting or reduced to short bristles 32. Asperella 



31B. Spikelets unlike, 3 at each node, the central one perfect, the lateral reduced, sterile 33. Hordeum 



30B. Inflorescence paniculate or digitate, rarely a spike with triangular axis bearing spikelets on 2 sides, or in a loose raceme. 

 36A. Leaf -blades linear, sessile. 



37A. Glumes distinct; palea with 2 keels; spikelets 1- to many-flowered. 



38A. Caryopsis with a hairy beak at apex; style lateral; leaf-sheaths cylLndric, with fused margins; spikelets usually 



rather large 34. Brotnus 



38B. Caryopsis not beaked; style terminal. 

 39A. Lemmas 5-nerved. 

 40A. Spikelets 1 -flowered. 



41A. Rachilla produced behind the palea as a naked bristle 35. Brachyelytrum 



41B. Rachilla obsolete 36. Aulacolepis 



40B. Spikelets 2- to many-flowered. 



42A. Spikelets prominently flattened, densely arranged on one side of the upper part of panicle-branches. 



37. Dactylis 

 42B. Spikelets flattened or somewhat so, arranged not only on one side of panicle-branches. 



43A. Lemmas glabrous or pubescent on back, often awned from apex 38. Festuca 



43B. Lemmas pubescent on midrib, awnless. 



44A. Lemmas rounded and not keeled at back, not webbed at base, with parallel nerves 39. Puccinellia 



44B. Lemmas keeled at back, with usually a tuft of long hairs at base, the nerves converging above. . .' 40. Poa 

 39B. Lemmas 7- to many-nerved. 



45 A. Lower florets fertile, the upper few reduced; inflorescence commonly a panicle. 

 46A. Callus of the florets glabrous; lemmas awnless (in ours). 



47A. Glumes 1- to 3-nerved, usually much shorter than the lemma; lemmas all alike; grasses of wet places. 



47AA. Leaf-sheaths closed 41. Glyceria 



47BB. Leaf-sheaths open 41a. Torreyochloa 



47B. Glumes 3- to 7-nerved, nearly as long as the lemma; lemmas of few upper florets neutral and usually dis- 

 similar to the fertile ones; grasses of mesophytic places 42. Melica 



46B. Callus bearded; lemmas awned; grasses of forests 43. Schizachne 



