ANALYSIS OF SPECIMENS. 23 



But little practice will be required to gain familiarity 

 in thus analyzing the flowers of the grasses. 



1. Spikeleta 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. Olumes 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. PalesB 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 tiie 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. 



18. Palese membranaceous, 14 



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



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



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 caTtilaginous, 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, 21 



