GRASS FAMILY. 95 
B. Spikelets 1-many-flowered; rachilla generally articulated above the two lower scales (below 
them in Nos. 32, 40, 48 and 54) and frequently extending beyond the flower in 1-flowered spikelets. 
Culms herbaceous. 
Spikelets upon pedicels in panicles, spike-like panicles or racemes, not in rows. 
Spikelets with but 1 perfect flower, which is terminal except in 37 and part of 36. 
Empty scales 4 (except in No. 20); palet 1-nerved. VI. PHALARIDEAE, 
Empty scales 2; palet 2-nerved. VII. AGROSTIDEAE. 
Spikelets with 2 or ‘more perfect flowers (except that one is staminate in Nos. 4o and 
45); upper flower often imperfect. 
Flowering scales generally shorter than the empty lower ones, usually with a bent 
awn on the back. VIII. AVENEAE. 
Flowering scales generally longer than the empty lower ones, unawned or witha 
straight awn from the apex. X. FESTUCEAE. 
Spikelets in two rows, forming a one-sided spike or raceme. IX. CHLORIDEAE. 
Spikelets in two opposite rows, forming an equilateral spike (unilateral in Vardus). 
XI. HORDEAE. 
Culms woody, at least at the base; tall reeds. XII. BAMBUSEAE. 
Tribe I. MAyDEAE. 
Fertile spikelets imbedded in the joints of the thick rachis. 1. Tripsacum. 
Tribe II. ANDROPOGONEAE. 
Joints of the rachis not much thickened nor excavated for the reception of the spikelets. 
Spikelets alike, perfect, one sessile, one pedicelled. 2. Erianthus. 
Spikelets not alike, the sessile perfect, the pedicelled staminate, empty or wanting. 
Inflorescence composed of spike-like silky racemes. 4. Andropogon. 
Inflorescence paniculate; spikelets silky. 
Pedicelled spikelet wanting (in our species). 5. Chrysopogon. 
Pedicelled spikelet present and usually staminate. 6. Sorghum. 
Joints of the rachis greatly thickened and excavated for the reception of the spikelets. 
3. Manisuris. 
Tribe III. Zoysreax. 
Spikelets in a terminal spike; second scale spiny. 7. Nazia. 
Tribe IV. PANICEAE. 
Spikelets without a subtending involucre of bristles or valves. 
Scales 3. 
Spikelets all alike in close 1-sided spikes. 
Spikelets with a swollen ring-like callus at the base. 10. Lriochloa. 
Spikelets without a callus. 8. Paspalum. 
Spikelets of two kinds, one borne in loose linear panicles, the other solitary on subterranean 
peduncles and maturing seed. 9. Amphicarpon. 
Seales 4, rarely 3 by suppression of the lowest one. 
Spikelets in 2’s or 3’s on one side of a long and slender flat or 3- eaeled rachis ; spikes digi- 
tate or approximate in whorls. Synther isma. 
Spikelets single, pedicelled, in panicles or raceme-like sessile and panaied spikes; first 
seale short, third empty or staminate, fourth fertile. 12. Panicum. 
Spikelets subtended by an involucre consisting of: 
I-many persistent bristles; spikelets in dense spikes, deciduous. 3. Lxophorus. 
2 spine-bearing valves forming a bur enclosing the spikelets and dectinous ‘with them. 
2 14. Cenchrus. 
Tribe V. ORYZEAE. 
Spikelets monoecious; tall aquatic grasses. 
Pistillate spikelets ovate, borne at the base of each branch of the panicle. 
15. Zizantopsts. 
Pistillate spikelets linear, borne on the upper branches of the panicle. 16. Zizanta. 
Spikelets not monoecious; grasses of swamps or wet grounds. 17. Homalocenchrus. 
Tribe VI. PHALARIDEAE. 
Third and fourth scales 
small and empty or rudimentary, not awned; stamens 3. 18. Phalaris. 
empty, awned upon the back; stamens 2. 19. Anthoxanthum. 
subtendi:fg staminate flowers with 3 stamens; fertile flowers with 2 stamens. 
20. Savastana. 
Tribe VII. AGROSTIDEAE. 
Flowering scale indurated at maturity, of firmer texture than the empty scales, and closely enve- 
loping the grain. 
Rachilla not prolonged beyond the palet. 
Flowering scale with a three- branched aw n; stamens mostly 3. a1. Aristida, 
Flowering scale with a simple awn. 
Flowering scale narrow; awn persistent. 
Awn tortuous or twisted, stout; callus evident. 22. Stipa. 
Awn straight, very slender; callus minute. 25. Muhlenbergia. 
Flowering scale broad; awn slender, straight, deciduous; callus obtuse. 
23. Oryzopstis. 
Flowering scale awnless. 24. Milium. 
Rachilla with a pedicel-like extension beyond the palet; stamens 2. 26. Brachyelytrum. 
