io8 GRAMINEAE. Vol. I. 



Fruiting scale and palet chartaceous or coriaceous, differing in color and appearance from 

 the remaining scales ; spikelets sometimes enclosed in an involucre. IV. Paniceae. 

 Spikelets laterally compressed ; hilum linear. V. Oryzeae. 



B. Spikelets articulated above the empty scales (below them in nos. 38, 41, 49, 57 and 64) which 

 are persistent, i-many-flowered ; rachilla sometimes extending beyond the uppermost scale. 

 Culms herbaceous, hence annual ; leaf-blades sessile, not articulated with the sheath. 

 Spikelets in panicles or racemes, usually upon distinct and often long pedicels. 

 Spikelets i-flowered. 



Empty scales 4; palets 1 -nerved. VI. Phalarideae. 



Empty scales 2 (rarely 1) ; palet usually 2-nerved. VII. Agrostideae. 



Spikelets 2-many-flowered. 



Flowering scales usually shorter than empty ones, awn dorsal, bent. VIII. Aveneae. 

 Flowering scales usually longer than the empty ones, awnless, or if awned the awn 

 terminal and straight, rarely dorsal. X. Festuceae. 



Spikelets borne in 2 rows : 



On one side of a continuous axis, forming i-sided spikes or racemes. IX. Chlorideae. 



On opposite sides of a continuous or sometimes articulated axis, forming equilateral 



spikes (unilateral in Nardus). XI. Hordeae. 



Culms woody, perennial ; leaf -blades petiolate, articulated to the sheath. XII. Bambuseae. 



Tribe I. Maydeae. 



Pistillate spikelets imbedded in the internodes of the thick rachis. 1. Tripsacum. 



Tribe II. Andropogoneae. 



Internodes of the rachis of the racemes thickened, appressed to the pedicels of the primary spike- 

 lets, thus forming excavations for the reception of the secondary or sessile spikelets ; fertile 

 flowering scales awnless. 2. Coelorachis. 



Internodes not thickened, and without excavations for the reception of the spikelets. 

 Spikelets all perfect, awned. 



Rachis of the racemes continuous ; panicle axis short, racemes subflabellate. 3. Miscanthus. 

 Rachis articulated ; panicle axis elongated. 4. Erianthus. 



Sessile spikelets perfect, the pedicellate staminate or empty, awnless, sometimes wanting. 



Inflorescence simple or compound, made up of 1 or more spike-like racemes which are 



sessile or on very short peduncles. 



Raceme single ; pedicels and internodes of the rachis clavate, spongy, usually stout, with 



a deep cup-shaped depression at the top. 5. Schizachyrium. 



Racemes not single ; pedicels and rachis-internodes filiform, or flat and linear, not 



spongy, nor appendaged at the apex. 



Racemes in pairs, or digitate in 5's or less, sessile, or only 1 pedunculate ; pedicels 



and internodes not sulcate nor with a median hyaline line. 6. Andropogon. 



Racemes numerous, on an elongated axis, more or less pedunculate ; pedicels and 

 internodes of the rachis with a median hyaline line. 7. Amphilophis. 



Inflorescence decompound. 



Pedicellate spikelet wanting. 8. Sorghastrum. 



Pedicellate spikelet present. 9. Holcus. 



Tribe III. Zoysieae. 



Spikelets in a terminal spike ; second scale spiny. 10. Nazia. 



Tribe IV. Paniceae. 



Spikelets without a subtending involucre of bristles or valves. 

 Spikelets all alike. 



Palets not enlarged when mature. 



Fruiting scale chartaceous the margins hyaline and flat. 



Spikelets in slender racemes borne toward the summit of the stem. 11. Syntherisma. 

 Spikelets in an open panicle on long pedicels. 12. Leptoloma. 



Fruiting scale indurated, rigid, the margins inrolled and not hyaline. 

 Opening in the fruiting scale turned toward the rachis. 



Spikelets with a swollen ring-like callus at the base ; fruiting scale mucronate or 



awn-pointed. 13. Eriochloa. 



Spikelets without a callus ; fruiting scale not mucronate. 14. Anastrophus. 



Opening in the fruiting scale turned away from the rachis. 



Spikelets plano-convex, in secund racemes, usually of 3 scales. 15. Paspalum. 

 Spikelets unequally bi-convex, in panicles, or rarely in secund racemes ; scales 4. 

 Scales or some of them awned; fruiting scale cuspidate. 16. Echinochloa. 

 Scales awnless. 



Second scale like the third, few-nerved not broad and saccate. 17. Panicum. 

 Second scale unlike the third, 1 1-13-nerved, broad, saccate. 18. Sacciolepis. 

 Palet in the axil of the third scale much enlarged and somewhat indurated when mature, 

 forcing the spikelet open. IQ . Steinchisma. 



Spikelets of 2 kinds, one in terminal panicles and not producing seed, the other subterranean 

 and perfecting seed. 20. Amphicarpon. 



Spikelets with an involucre : 



Of bristles, persistent; inflorescence a dense cylindric spike-like panicle. 21. Chaetochloa. 

 Of 2 spine-bearing valves enclosing the spikelets, deciduous with them. 22. Cenchrus. 



Tribe V. Oryzeae. 



Spikelets unisexual ; plants monoecious ; tall aquatic grasses. 



Pistillate spikelets ovate, at the base of each branch of the panicle. 23. Zizaniopsis 



Pistillate spikelets linear, on the uppor branches of panicle. , 24'. Zizania 



Spikelets all perfect, broad, compressed; in swamps or wet grounds. 25. Homalo'cenchrus. 



