(GRASS FAMILY.) 537 



* Spikelets imperfectly several-flowered, but only one perfect flower, and this intermediate ! 

 the one or two below it, and as many above, neutral. 



17. CTENIUM. Spikelets closely imbricated on one side of the axis of a single curved spike. 



* * * Spikelets with one perfect flower below and one or more neutral ones or rudiments above. 



18. BOUTELOUA. Lower palea 3-eleft and pointed o>3-awned at the apex. Spikes dense. 



19. GYMNOPOGON. Lower palea and the rudiment 1-awned Spikes filiform, racemed. 



20. CYNODON. Flower and the rudiment awn less. Spikes slender, digitate. 



if * * * Spikelets several-flowered ; more than one of the lower flowers perfect and fertile. 

 H- Spikes digitate at the summit of the culm, dense. 



21. DACTYLOCTENIDM. Glumes compressed-keeled ; outer one awned : lower palea pointed. 



22. ELEUS1NE. Glumes and palea both awuless and blunt. 



<- *- Spikes racenied, slender. 



23. LEPTOCHLOA. Spikelets loosely spiked, Lower palea pointless or awned at the tip. 

 Subtribe 4. FESTUCINE.S:. Spikelets several- (few -many-) flowered, pauicled ; the upper- 



most flower often imperfect or abortive. Paleae pointless, or the lower sometimes tipped 

 with a straight (not twisted nor deeply dorsal) awn or bristle. Stigmas projecting from 

 the side of the flower. Stamens 1 - 3. 



* Culms herbaceous. Spikelets with the lower flowers all perfect. 



t- Grain free from the paleac. (Also free in one or two species of No. 36.) 



** Joints of the rhachis of the spikelet at the insertion of each flower, or the whole rhachis, 



bearded Paleae convex, not laterally compressed Glumes and palea; memhranaceous. 

 21. TKICUSPIS. Spikelets 3 -many-flowered Lower palea hairy-fringed on the 3 nerves, one 

 or all of which project into awns or mucronate tips, mostly from notches or clefts. 



25. DUPONTiA. Spikelets 2 - 3-flowered. Lower palea scarious, entire and awnless. 



H- -w- llhachis of the spikelet and base of the flower not bearded. 

 H Lower palea 1-poiuted. awned, or acute, the nerves when present running into the point. 



26. DIARRHENA. Glumes (short) and the rigid-pointed lower 3-nerved palea coriaceous, 



convex-boat-shaped. Stamens 2. Pericarp cartilaginous, large. Panicle loosely few- 

 flowered. 



27. DACTYLIS. Glumes (rather long) and lower palea awn-pointed, herbaceous, compressed- 



keeled. Panicle contracted iu one-sided clusters. 



28. KCELERIA. Glumes (nearly as long as the spikelet) and lower palea membranaceoiis, 



keeled, acute or mucronate, or rather blunt Panicle contracted, spike-like 

 ITU Lower palea awuless and pointless, blunt (except one Glyceria), the nerves parallel. 

 a. Glumes extremely dissimilar, l - 3-flowered. 



29. EATONIA. Lower glume linear ; the upper broadly obovate and folded round the flowers. 



b. Glumes alike, but often unequal in size 



30. MELICA. Lower palea flattish-couvex, many-nerved, membranaccous at the top, hard- 



ening on the loose grain. Fertile flowers 1-3, the upper enwrapping some deformed 



sterile flowers 

 81. GLYCERIA. Lower palea convex or rounded on the back, 5 - 7-nerved, scarious at the 



tip. Spikelets many-flowered ; the flowers commonly deciduous at maturity by the 



breaking up of the rhachis into joints. 

 32. BRIZOPYRUM. Lower palea laterally compressed and often keeled, acute, rigid, rather 



coriaceous, smooth, faintly many-nerved. Spikelets flat, spiked- clustered. 

 33 POA. Lower palea laterally compressed and mostly keeled, 5-uerved, menibranaceous, 



scarious-margiued, the margins or nerves below often cobwebby or pubescent : the 



upper palea not remaining after the lower falls. Spikelets flattened 

 84. ERAGROSTIS. Lower palea 3-nerved, keeled, deciduous, leaving the upper persistent on 



the rhachis. Spikelets flat. 



(- - Grain adherent to the upper palea 

 86. BR1ZA. Lower palea rounded and very obtuse, pointless, many -nerved, flattened parallel 



to the glumes, becoming ventricose, broadly scarious-margiaed. Spikelets compressed, 



somewhat, heart, shaped 

 86 FESTUCA. Lower palea convex on the back, acute, pointed, or invited at the tip, few- 



nerve 1. Spikelet* terete or fiatflish. Stales terminal. 



