ANALYSIS OP SPECIMENS. 23 



But little practice will be required to gain familiarity 

 in thus analyzing the flowers of the grasses. 



]. Spikelets with but one flower 2 



1. Spikelets with two or more flowers, 26 



2. Flowers arranged in panicles 3 



2. Flowers in spikes 16 



3. With awns, 4 



3. Without awns, 12 



4. Glumes large, 5 



4. Glumes minute, umqual, one hardly perceptible 11 



4. Glumes none, grass aquatic, 2 — Zizania. 



5. Without abortive rudiments . . ._ 6 



5. With an abortive rudiment of a second flower 52 — Holous. 



6. Falese two, 7 



6. Palese three, upper awned flowers polygamous, . 65 — Sorghum. 



7. Palea with one awn, , 8 



7. Lower palea with three twisted awns 15 — Aristida. 



8. Palese cartilaginous or gristly, 9 



8. Palese herbaceous 10 



8. Palese membranaceous, panicle open, 7 — Agrostis. 



8. Palese membranaceous, panicle contracted, . . .8 — Polypogon. 

 9. Flowers sessile, or joined to the stem at the base, . . 13 — Oryzopsis. 



9. Flowers stipitate, fruit black 14 — Stipa. 



10. Flowers naked, with one stamen, 9 — Cinna. 



10. Flowers hairy, stamens three, 12 — Calamagrostis.. 



11. Stamens three 10 — Muhlenbergia. 



11. Stamens two, 11 — Brachyelytrum. 



12. Glumes two, 13 



12. Glumes none, leaves rough from the end backwards, 1 — Leersia. 



13. Palese membranaceous, 14 



13. Palese leathery, spikelets all cauline, 5G — Milium. 



13. Palese leathery, fertile spikelets radical, .... 57 — Amphicarpon. 



14. Fruit coated, or covered with a husk, 15 



14. Fruit naked, 6 — Sporobolus. . 



15. Flowers stalked, 7 — Agrostis. 



15. Flowers sessile, 5 — Vilfa. 



16. Flowers awned, 17 



16. Flowers without awns, 22 



17. Spikes solitary 18 



17. Spikes many, awnless, unilateral, palese cartilaginous, 59 — Panicum. 



17. Spikelets two, fertile, 63— Erianthus.. 



17. Spikes two, polygamous, sterile flowers bearded, . . 64 — Andropogon 



18. Spikes simple, or nearly so 19' 



18. Spikes paniculate, or lobed, 21i 



