62 Wisconsin Academy of Sciences, Arts, and Letters. 
6. Spikelets readily deciduous at maturity; lemma awned below the 
middle.ALOPECURUS. 
Spikelets not deciduous; lemma awnless.PHLEUM. 
7. Lemma one, rarely three-nerved, awnless; pericarp readily separat¬ 
ing from the grain.SPOROBOLUS. 
Lemma three to five-nerved, awned or awnless; pericarp adherent 
to the grain.8. 
8. Florets sessile; stamens three.9. 
Florets plainly stalked; stamen one..CXNNA. 
9. Rhachilla not prolonged behind the palea.AGROSTIS. 
Rhachilla prolonged behind the palea into a bristle.10. 
10. Panicle loose or contracted, callus and prolonged rhachilla with 
long hairs. CALAMAGROSTIS. 
Panicle dense, spike-like, callus and prolonged rhachilla with 
short hairs.AMMOPHILA. 
Tribe AVENEAE. 
1. Spikelets articulated below the glumes, falling entire or with 
glumes and lowest floret together; florets usually awnless.... 
.SPHENOPHOLIS. 
Articulation above the glumes; glumes not falling off with the 
spikelets; awns present.2. 
2. Awns dorsal dorsal, not flattened.3. 
Awns from between the teeth of the bidentate apex of the lemma, 
flattened and twisted.DANTHONIA'. 
3. Spikelets two to several-flowered, lowest floret perfect.4. 
Spikelet two-flowered, lower floret staminate, long-awned, upper 
perfect and usually awnless.ARRHENATHERUM. 
4. Spikelets less than one centimeter long, grain free from the palea. 
.5. 
Spikelet more than 1 cm. long; grain adherent to the palea. 
.AVENA. 
5. Lemma keeled, bidentate, awns arising from above the middle. 
. TRISETUM. 
Lemma convex, awn arising at or below the middle. 
.DESCHAMPSIA. 
Tribe CHLORIDEAE. 
Spikelets one flowered, all alike; rhachilla articulated below the 
narrow, unequal glumes...SPARTINA. 
f 
Tribe FESTUCEAE. 
1. Rhachilla with long hairs enveloping the lemma; tall aquatic 
grasses.PHRAGMITES. 
Rhachilla and lemma naked or hairy; hairs much shorter than the 
lemma . ••••*•• * 
2. Spikelets of two forms, the fertile 1-3 flowered, surrounded by the 
sterile consisting of many pectinate scales.CYNOSURUS. 
Spikelets all alike. o. 
3 Lemmas 1-3 nerved, all with perfect flowers, or the upper staminate 
or empty. ERAGROSTIS. 
Lemmas 5-many nerved, each with a perfect flower, or the upper¬ 
most sometimes aborted. 4. 
4. Scales more or less strongly compressed or keeled.5. 
Scales rounded on the back, at least below.*>. 
