ANALYSIS OF SPECIMENS. 23 



But little practice will be required to gain familiarity 

 in thus analyzing the flowers of the grasses. 



1. 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, unequal, one hardly perceptible, 11 



4. Glumes none, grass aquatic, 2 Zizania. 



5. Without abortive rudiments, 6 



6. With an abortive rudiment of a second flower, 52 Holcus. 



6. Paleaj two, 7 



6. Palege three, upper awned flowers polygamous, . 65 Sorghum. 



7. Palea with one awn, 8 



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



8. Paleae cartilaginous or gristly, 9 



8. Paleae herbaceous, 10 



8. Paleae membranaceous, panicle open, 7 Agrostis. 



8. Paleae 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. Paleae membranaceous, 14 



13. Paleae leathery, spikelets all cauline, 56 Milium. 



13. Paleae 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, paleae cartilaginous, 59 Panicum. 



17. Spikelets two, fertile, 63 Brian thus. 



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



18. Spikes simple, or nearly so, 19 



18. Spikes paniculate, or lobed, 21 



