ORDER 156. GR AMINES. 771 



TRIBES AND GENERA. 



| Spikelet 1-flowered with no apparent rudiment of ti second fl. (2) 

 Spikelet 2-flowered, one of the fls. sterile or rudimentary. (7) 



<j Spikelet 3-flowered, the 2 lower (lateral) fls. sterile or rudimentary, (i) Tribo 8 



Spikelet 2 oo-flowered, 2 or more of the fls. perfect. (9) 

 2 Inflorescence paniculate. (3) 



2 Inflorescence strictly spicate, spikes equilateral. (5) 

 2 Inflorescence strictly spicate, spikes unilateral. (6) 



3 Glumes none (or minute and the stamens 6). (a) Tribe I 



3 Glumes present, at least 1 conspicuous. (4) 



4 Pales of the flower thin and soft, often awned. (b) Tribo 9 



4 Pales of the flower coriaceous, tipped with awns, (f ) Tribe 4 



awnlcss. (g) Tribe 5 



6 Spikes cylindric, the spikelets condensed all around, (e) Tribe 9 



5 Spikes prismatic, spikelets sessile in rows, (v) Tribe 9 



6 Spikelets rounded on the back, appresscd to the rachis. (g) Tribe 5 



6 Spikelets acutely keeled on the back, imbricated on each other, (x) ) T >. 



7 Upper fls. of the spikelet abortive. Fls. in unilateral spikes, (x) ) f 



Fls. paniculate, (k) Tribo T 



7 Lower flower of the spikelet abortive. (8) 



8 Pales coriaceous, firmer in texure than the gls. Paniculate, (g) Tribe 5 



8 Pales membranous, thinner than the glumes. Spicate. (bb) Tribo 11 



9 Flowers in 2 or 4-rowed, equilateral spikes, (v) Tribe 9 



unilateral spikes, (x) Tribo 18 



9 Fls. in panicles more or less diffuse. (10) 



10 Pale awned at the tip or awnless. (n) Tribe 8 



10 Pale awned on the back or below the tip. (k) Tribe T 



TR. 1. ORYZE^E. (Spikelets 1-flowered, panicled. Gls. obsolete. Stam. 16.) 



a Flowers perfect, flattened laterally, awnless. Gl. 0. Stam. 2 or 3 LEERSIA, 1 



Gl. minute. Stam. 6 OBTZA. 2 



a Flowers monoecious, convex on the back, awned. Stamens 6 ZIZANIA. 3 



TR. 2. AGROSTIDE^E. (Spikelets 1-flrd., panicled. Gl. and pales thin. Grain free.) 



b Fls. surrounded at base with a tuft of long, silky hairs CALAMAGROSTIS. 9 



b Fls, naked or thinly bearded at base, (c) 



C Glumes both long-awned and longer than the awned pales POLYPOGON. 8 



C Glumes both awn -pointed (or minute and the pale awned) MUHLBNBEBGIA. 7 



c Glumes awnless, conspicuous, (d) 



d Pale stalked in the glumes, awned on the back, monandrous CINNA. 6 



d Pale sess. in the gls. 3-androus, acute, awnless. Gls. shorter SPOROBOLUS. 5 



obtuse, often awned on the back. . . . AGROSTIS. 4 



TR. 3. PHLEOIDE^E. e Gls. united at base, awnless. Pale 1, awned ALOPECUBUS. 10 



e Gls. distinct, mucronate. Pales 2, awnless PHLEUM. 11 



TB. 4. STIPACE^. f Awn of the flower simple, straight, deciduous ORYZOPSIS. 14 



f Awn of the flower simple, twisted, very long STIPA. 13 



f Awn of the flower triple or 3-parted ARISTIDA. 12 



TR. 5. PANICIEJE. (Spkl. 2-fl., lower fl. abortive. Gls. very unequal. Pale coriaceous.) 

 g Spkl. apparently 1-flowered, the lower glume wanting and the single abortive pale 



supplying its place. Fls. spicate, unilateral PASPALUM. 15 



Fls. diffusely panicled, all alike MILLIUM. 16 



Fls. paniculate, 2 sorts, one under ground AMPHICARPUM. 17 



g Spkl. evidently 2-flowered, both gl. present, abort, fl. neutral or $ . (h) 



li Fls. paniculate, without awns or spines. Gl. very unequal PANICXTM. 18 



with the glumes and pale coarsely awned OPLISMBNPS. 19 



h Fls. spike-panicled, each with an invol. of awned pedicels SETAEIA. 20 



each with a hardened, burr-like invol CENCHRUS. 21 



TR. 6. PHALARIDE^E.i Sterile fls. 2 minute rudiments. Panicle spicate PHALABIS. 22 



i Sterile fls. 2 awned pales. Panicle spicate.. . .ANTHOXANTHUM. 23 



i Sterile fls. both 2-valved, $ . Panicle open HIEROCHLOA. 24 



TR. 7. AVENE^E. (Spkl. 2 00 -flrd., panicled. Gls. large. Pale awned below the tip.) 



k Spikelet with 1 perf. flower and 1 awned stam. flower above HOLCCS. 25 



below ABRHENATHKRUM. 28 



k Spikelet with definitely 2 perfect fls. Pale subentire, awn dorsal AICA, 26 



k Spikelet with 2 or more perfect fls. Pale 2-toothed at apex, (m) 



