POACEAE. 



A. Spikelets falling from the pedicel entire (see also no. 22 of section B) naked or 



enclosed in bristles or sometimes in a bur-like involucre, or immersed in 'the 



mternodes of a readily disarticulating rachis, 1-flowered, or if 2-flowered the 



lower flower staminate; no upper empty scales : rachilla not extending beyond 



the uppermost scale. " "jc^wiiu 



Spikelets round or somewhat dorsally compressed : empty scales manifest • hilum 



punctiform. 



Flowering scale and palet hyaline, thin, much more delicate in structure than 



the thick-membranous to coriaceous empty scales. 



Spikelets unisexual, the pistillate borne in the lower, the staminate in the 



upper, part of the same spike. Tribe I. MAYDEAE 



Spikelets in pairs, one sessile, the other 

 pedicellate, the former perfect, the 

 latter sometimes perfect, more com- 

 monly with a staminate flower, often 

 empty or reduced to one or two 

 scales, or occasionally wanting. 

 Flowering scale, at least that of the perfect 

 flower, similar in texture to the empty 

 scales, or frequently thicker and firmer, 

 never hyaline and thin. 

 Spikelets much compressed laterally : empty 



scales none or rudimentary: hilum linear. 



B. Spikelets with the empty scales persistent, the rachilla hence articulated above 



them (below them in no. 22 and the spikelet falling from the pedicel entire), 

 1-many-flowered ; frequently the upper scales are empty : rachilla often pro- 

 duced beyond the uppermost scale. 

 Spikelets borne in open or spike-like panicles or racemes, usually upon distinct and 

 often long pedicels. 

 Spikelets 1 -flowered. 

 Spikelets 2-many-flowered. 



Flowering scales usually shorter than 

 the empty ones, the awn dorsal and 

 usually bent. 

 Flowering scales usually longer than 

 the empty ones, the awn terminal 

 and straight, rarely dorsal, some- 

 times wanting. Tribe VII. CHLORIDEAE. 

 Spikelets in two rows. Tribe VIII. FESTUCEAE. 



Tribe II. ANDROFOGONEAE. 



Tribe III. PANICEAE. 

 Tribe IV. ORYZEAE. 



Tribe V. AGROSTIDEAE. 



Tribe VI. AVENEAE. 



Tribe I. MAYDEAE. 



Fertile spikelets imbedded in the internodes of the thick 

 rachis. 



Tribe II. ANDROFOGONEAE. 



Some or all of the racemes sessile. 



All of the racemes more or less pedunculate. 



Pedicellate spikelets present and usually staminate. 



Pedicellate spikelets wanting. 



1. Tripsaccm. 



2. AXDROPOGON. 



3. HOLCUS. 



4. SORGHASTRUM. 



Tribe III. PANICEAE. 



Spikelets not sunken in the rachis. 

 Spikelets naked, not involucrate. 

 Empty scales 2. 



Lower empty scale with a thickened ring-like 



callus. 5. PAsrALUJi. 



Lower empty scale unappendaged. 



Spikelets ovate to orbicular, usually obtuse, 



rarely acute. 6. Eriochloa. 



Spikelets lanceolate, acute or acuminate. 7. Syntherisjia. 



Empty scales 3. 



Empty scales awned or awn-pointed. 



Stems erect : leaf-blades long and narrow : 



racemes usually of many spikelets. 9. Echinochloa. 



Stems creeping : leaf-blades short and broad : 



racemes or clusters usually of few spikelets. 10. Oplismenus. 

 Empty scales not awned. 



Stems and branches not woody nor bamboo-like. 



Fruiting scale rigid, the margins inrolled. 11. Panicum. 

 Fruiting scale not rigid, the hyaline mar- 

 gins not inrolled. 

 Spikelets in very slender, one-sided, 

 racemes which are usually whorled 

 or approximate. 7. Syntherisjia. 



