536 GiiA?,i!xi:^:. (GRASS FAMILY.) 



Subtribe 2. AQROSTIDE^I. Spikclcts 1-flowered, perfect, occasionally with the rndiment cr 

 abortive pedicel of a second flower above, panicled, or the panicle sometimes contracted 

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



* PnLKOiT>EJ5. Glumes equal, strongly keeled, laterally flattened, boat-shaped, somewhat her- 



baceous, as well as the paleae. Squarnulre 2. Grain free. Inlloresccuce densely spiked. 



3. ALOPECURUS Glumes united at the base. Lower paleu awned, the upper wanting. 



4. PULEUM. Glumes distinct. Palcae 2, the lower truncate and awnless. 



* * TRUE AGROSTIDE.S;. Glumes equal, or often unequal, concave or keeled, inembranaceous. 

 Palea> inembranacpons (except in part of No. 12). Squamuloe 2. Grain free Inflorescence 

 psinieled, open, or often contracted (glomerate), but not strictly spiked. 



*- Glumes and paleae neither awned, bristle-bearing, nor inucronate, nuked. Flower sessile in 

 the glumes, naked at the base ; the lower paleu 1-nerved. Fruit deciduous 



6. V1LFA ft.-ed adherent to the closely investing pericarp, forming a caryopsis, or true gralu, 



as in most Grasses. Panicle spiked or contracted. 



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

 *- - Glumes or the (3 - 6-nerved) lower palea awned, bristle-pointed, or mucrocate (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 the lower one rather longer, pointless, exceeding the very 



thin blunt pale.-e. 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 palese, the lower 



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



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



similar paleae. Stamen 1. Paleae raised on a distinct naked stalk, beardless, the lower 

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



10. MUHLKNHKIIGIA. Lower glume mostly smaller. Paleae chiefly hairy-bearded at the 



li.^c, Mie tip of the lower one mucronate-pointed or awned. Stamens 3. 



11. BRAC1IYELYTRUM Lower glume nearly obsolete, and the upper minute. Lower pale 



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. 

 - -4- t- Glumes and paleae not bristle-pointed. Flower hairy-tufted at the base. 



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



* * STIPES. Paleae 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 Squamulse mostly 3. Inflorescence racemose or 

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



18. ORYZOPSIS. Awn simple, straight, deciduous from the palea, or sometimes wanting. 



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



15. AKISTIDA. 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 acquaints 1 

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



66. PHALAK1S. Spikelets laterally flattened. A rudiment at the base of each palea. 

 60. MILHIM. Spikelets dorwilly flattish, not jointed with the pedicels : flowers all alike. 



67. AMPIIK'AKPi'M. Spikelets of two sorts, the fertile subterranean, those of the panicle 



separating by a joint without ripening grain. 



Bnbtribe 3 CHLORIDES. Spikelets (rarely 1-flowered, usually) 2 - several-flowered, with one 

 or more of the upper flowers imperfect, disposed in one-sided spikes ! Glumes persist- 

 ent, the upper one looking outward. Rhachis (axis) jointless. Spikes usually rucuuu>d 

 or digitate. Stamens 2 or a 



* Spikelets strictly 1-flowered. 



68. PASPALUM might be looked for here, having to all rtpiiennn.o' merely 1-flowered sj D 

 Vj. SI'AKT. INA. SpikeJets imbricated 2-ranked, flat, crowded iu alternate spikes. 



