536 GRAMTNF.JE. (GRASS 1'AMILT.) 



Subtribe 2. AaROSTiPE^. Spikclets 1 -flowered, perfect, occasionally with the rudiment Of 

 abortive pedicel of a second tlowcr above. pai,id,'d, or the panicle sometimes contracted 

 into a cylindrical spike or head. Stamens 1-3. 



PnLEOiT>K.E. Glumes equal, strongly keeled, laterally flattened, boat-shaptd, somewhat her- 

 baceous, as well as the pale;i>. Squamul;e 2. drain free. Inflorescence densely spiked. 



3. ALOPECUKUS Glumes united at the base. Lower pak.i awned, the upper wanting. 



4. PIILEUM. Glumes distinct. 1'ah ;e 2, the lower truncate and jtwnless 



* TRUE AoROSTinE.'E. Glumes equal, or often unequal, concave or keelvd, membranaceous. 

 Palea 1 membranaceous (except in part of No. 12). Squamulse 2. drain free Inflorescence 

 panicled, open, or often contracted (glomerate), but rot strictly spiked. 



+- Glumes and pulc;e neither a\vned, bristle-bearing, nor mucronate, naked. Flower sessile in 

 tbe glumes, naked at the base ; (lie lower palea 1-nerved. Fruit deciduous. 



6. TILFA. Seed adherent to the elo.- ely investing pericarp, fovmingacaryopsis, or true grain, 



as in most Grasses. Panicle spiked or eontrarted 



6 SPOROBOLUS. Seed loose in the pericarp (utricle) Panicle spiked or diffuse. 

 - *- Glumes or the (3 6-nerved) lower palea awned, bristle-]>ointed, or mucronate (except in 

 some species of Agrostis) Flower raised on a more or less evident stalk (callus) in the 

 glumes, naked, or barely hairy, at the base 



7. AGROSTIS. Glumes equal, or tbe lower one rather longer, pointless, exceeding the very 



thin blunt palea; . Lower palea pointless, commonly awned on the back ; the upper 

 sometimes wanting. Panicle open. 



8. POLYPOGON. Glumes nearly equal long-awned, much longer than the palesc, the lower 



of which is often short-awned below the apex. Stamens 3 Panicle contracted. 



9. CINNA. Glumes acute, the loner about equalling, and the upper slightly exceeding, the 



similar paleae. Stamen I Palea- raised on a distinct naked stalk, beardless, the lower 

 one short-awned or bristle-pointed just below the tip ; the upper 1-nerved. 



10. MUHLENBEHGIA. Lower glume mostly smaller. Pakw chietly hairy-bearded at tl 



base, the tip of the lower one mucronate-pointed or awned. Stamens 3. 



11. BRACHYELYT RUM Lower glume nearly obsolete, and the upper minute. Lower palenB 



long-awned from the tip ; the upper grooved on the back and bearing a long and slen- 

 der naked pedicel of an abortive second flower. Stamens 2. 

 *--- Glumes and paleae not bristle-pointed. Flower hairy-tufted at the base. 



12. CALAMAGROSTIS. Lower palea mostly awned on the back, shorter than the glumes. 



* * * STJPEJB. Palere coriaceous, or indurated in fruit, commonly shorter than the membra- 

 naceous glumes, on a rigid callus ; the lower involute, terete, closely enclosing the upper and 

 the grain, mostly 1-3-awned at the apex Squamula? mostly 3 Inflorescence racemose or 

 panicled : spikelets usually large, the flower deciduous from the persistent glumes. 



13. ORYZOPS1S. Awn simple, straight, deciduous from the palea, or sometimes wanting. 



14. STIPA. Awn simple, twisted below. Callus pointed at the base 



15. ARISTIDA. Awn triple. Upper palea small. Callus pointed at the base 



* * * * Palea coriaceous or cartilaginous, awnless. Here the following would be sought by the 

 student who overlooked the pair of rudimentary flowers in No 55, and was not acquainted 

 with the recondite theoretical structure of No. 56 and 57. 



55. PHALAHKS. Spikelets laterally flattened. A rudiment at the base of each palea. 



56. MILTUM. Spikelets dorsal ly flatfish, not jointed with the pedicels : flowers all alike. 



67. AMPmCAKPUM. Spikelets of two sorts, the fertile subterranean, those of the panicle 



separating by a joint without ripening grain 



Sabtribe 3 <'HI,OIUJ>K.<>:. Spikelets (rarely 1 -flowered, usually) 2 several-fit wercd, with one 

 or more <>f the irppcr flowers imperfect, disposed in one-sided spikes! Glumes persist- 

 ent, the upper one looking outward Khachis (axis) jok.tle;->s Spikes usually racemed 

 or digitate. Stamens, 2 or 3 



* Spikelets strictly 1-flowered. 



68. PASPALUM might be looked for here, having to all appearance merely 1-flowcred spikeleta 

 16 SPART1NA. Spikelets imbricated, 2-rauked, flat, crowded iu alternate spikes. 



