487 
20. Stenotaphrum. Spikelets with one perfect and one staminate floret. 
B. Spikelets laterally compressed. 
Tribe V. Spikelets unisexual and monoccious or perfect, in loose panicles: empty 
glumes wanting orrudimentary: palet often 1-nerved: stamens often 6.—ORYZE&. 
* Spikelets unisexual, linear; pistillate spikelets awned. 
21. Zizania. Upper branches bearing pistillate spikelets; lower ones staminate. 
22. Zizaniopsis. All the branches bearing pistillate spikelets near the extremi- 
ties and staminate ones near the bases, 
* * Spikelets perfect, oblong, much compressed. 
23. Homalocenchrus. Spikelets awnless. 
Tribe VI. Spikelets with one perfect terminal floret and two lateral rudimen- 
tary florets, in contracted or spike-like panicles: empty glumes present: palet 
l-nerved or wanting.—PHALARIDE_E. 
24, Phalaris. Empty glumes equal: neutral florets reduced to small scales, 
25. Anthoxanthum. Empty glumes unequal: neutral florets awned. 
Series I]. PoACKA, Spikelets 1 to many-flowered, imperfect floret 
uppermost, if present; if unsexual, more than 3-flowered: internode 
of rachilla somewhat elongated, articulated usually above the empty 
glumes, sometimes at the base of each floret. 
A. Culm herbaceous: leaf-blade not narrowed to a petiole. 
a. Spikelets upon distinct (sometimes very short) pedicels, cuneate-clustered in 
racemes, or often solitary in panicles, these sometimes contracted and spike-like, 
but never in unilateral spikes. 
Tribe VII. Empty glumes 2: perfect floret solitary or with an obscure rudiment: 
palet 2-nerved or absent (1-nerved in No, 29,)—AGROSTIDE®. 
Subtribe 1. Floral glume coriaceous or chartaceous, much firmer in texture than 
the empty glumes, closely convolute about the palet and grain, awned: florets borne 
on stipes.—Stipee. ’ 
26. Aristida. Awn trifid (lateral divisions often short). 
27. Stipa. Awnsimple, twisted, ratherstout, stipe, hairy; sharp and prominent, 
28. Oryzopsis. Awn simple, slender, often caducous; stipe obtuse. 
33. Muhlenbergia. Awn simple, slender; stipe very small. 
Subtribe 2. Floral glume very thin, herbaceous or membranaceous, loosely or not 
at all convolute about the grain, short-awned or awnless.—Fuagrostee. 
* Floral glume 3 to 5-nerved, 2-toothed, short awned from the sinus. 
+ Stamen 1. 
29. Cinna. Floral glume raised on a distinct naked internode of the rachilla: 
palet 1-nerved. 
+ + Stamens 3. 
30. Polypogon. Empty glumes awned: panicle contracted. 
31. Limnodea. Empty glumes awnless: panicle open. 
* * Floral glumes 1 or indistinctly 3-nerved, short awned from the apex or between 
the two minute teeth or awnless: florets equaling or usually exceeding the empty 
glumes, 
