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. 



6. Without abortive rudiments, 6 



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



6. Palese two, . 7 



6. Pale* 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. Paleae membranaceous, panicle contracted, . . .8 Polypogon. 

 9. Flowers sessile, or joined to the stem at tie base, . . 13 Oryzopsia. 



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. Paleaj membranaceous, 14 



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



13. Paleaa 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, palete cartilaginous, 59 Panicum. 



17. Spikelets two, fertile, 63 Erianthua. 



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



18. Spikes simple, or nearly so 19 



18. Spikes paniculate, or lobed, 21 



