ORDER 15G.GR AMINES. 771 



TRIBES AND GENERA. 



Spikelet 1-flowered with no apparent rudiment of a second 3. (2) 

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



Spikelet 3-flowered, the 2 lower (lateral) fls. sterile or rudimentary, (i) Tribe 6 



Spikelet 2 CO -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 1 



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



4 Pales of the flower thin and soft, often awned. (6) Tribe 2 



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



ewnless. (g) Tribe 5 



5 Spikes cylindric, the spikclets condensed all around, (e) Tribe 3 



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



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



6 Spikelets acutely keeled on the back, imbricated on each other, (x) } T > ^ 1) 



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



Fls. paniculate, (k) Tribe 7 



7 Lower flower of the spikelet abortive. (8) 



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



8 Pales membranous, thinner than the glumes. Spicate. (bb) Tribe 1 1 



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



unilateral spikes, (x) Tribe 10 



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



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



1O Pale awned on the back or below the tip. (k) Tribe 7 



TB. 1. OEYZE.E. (Spikelets l-flowered, panicled. Gls. obsolete. Stain. 1 C.) 



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



Gl. minute. Stam. 6 ORYZA. 2 



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



TB. 8. AGEOSTIDE.^. (Spikelets 1-flrd., panicled. Gl. and pales thin. Grain free.) 



b Fls. surrounded at base with a tuft of long, silky ^airs CALASI AGKOSTIS. 9 



b Fls. naked or thinly bearded at base, ^c) 



c Glumes both long-awned and longer than the awned pales. POLVPOGON. 8 



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



C Glumes awnless, conspicuous, (d) 



d Pals stalked in the glumes, awned on the back, monandrous CIXXA. 6 



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



obtuse, often awned on the back AGROSTIS. 4 



TE. 3. PIILEOIDE^E. e Gls. united at base, awnless. Pale 1, awned ALOFECL-RUS. 10 



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



Tu. 4. STIPAOE-iE. f Awn of the flower simple, straight, deciduous ORTZOPSIS. 14 



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



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



TB. 5. PANICIE.E. (Spkl. 2-fL, lower fl. abortive. Gls. very unequal. 5 Pale coriaceous.) 

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



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



Fls. diffusely panicled, all alike MILLIUM. 1C 



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



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



h Fls. paniculate, without awns or spinep. Gl. very unequal PAXICCM. IS 



with the glumes and pale coarsely awned OPLISMESTS. 11> 



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



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



TK. 6. PLALARIDEJE. i Sterile fls. 2 minute rndiments. Panicle spicate PHALARIS. 22 



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



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



Ts. 7. AVENEJS. (Spkl. 2 co-flrd., panicled. Gls. large. Pale awned below the tip.) 



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



below AP.RHESATHKEL-.M. 2^ 



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



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



