70 Graminaceae 
E. Glumes exceeding the lower lemma (less the awns); lemma-awns erect, 
not at all divergent. E. (A. caninum.) 
A. richardsoni Schrad. 
EE. Glumes shorter than the lower lemma (less the awns); lemma-awns di- 
vergent or widely spreading. 
F. Glumes attenuate into a scabrous awn. 
G. Spikes 4—7 cm. long; rachis readily breaking at joints; glumes 
5—8 mm. long (less the awn). C. E. 
A. seribneri Vas. 
GG. Spikes 10—25 cm. long; rachis not readily breaking at joints; 
glumes 10—14 mm. long (less the awn). E. 
A. gmelini S. & S. 
FF. Glumes awnless. 
H. Leaves glabrous or nearly so. 
I. Lemma-awn O0—1I cm. long. E. (A. divergens tenuispicatum; A. 
spicaitum tenuispicatum; A. divergens.) 
A. spicatum S..& S. (Wheat Bunch-grass) 
II]. Lemma-awn 1.2—2.5 cm. long. E. (A. divergens inerme; A. 
vaseyi; A. spicatum vasevi.) 
A. spicatum inerme Hel. 
HH. Leaves pubescent on both sides. E. 
A. spicatum puberulentum Pip. (Wire Bunch-grass) 
DD. Lemma-awns shorter than their lemmas or none. 
J. Spikelets flattened. (See II.) 
ane Spikelets terete or nearly so. 
K. Lower glume 3-veined. 
L. Leaves 3.5—-9 cm. long; glumes scabrous on the keel. E. 
A. brevifolium Scribn. 
ue. Leaves 7.520 cm. long; glumes scabrous on the margin. E. 
A. biflorum R.'& S. 
KK. Lower glume 5-veined. 
M. Spikes 3—10 cm. long; glumes mostly widest above their middle. E. 
A. violaceum Vas. 
MM. Spikes 8—20 cm. long; glumes mostly widest below their middle. 
E. (A. tenerum longifolium; A. pseudorepens; A. pseudorepens mag- 
num. ) A. tenerum Vas. 
AA. Plants not tufted, stems from creeping rootstocks. 
N. Lemma hairy. 
©. Lemma villous; spike rather dense. 
P. Spikelets 5—7-flowered. E. (A. dasystachyum subvillosum.) 
A. subvillosum Pip. 
PP: Spikelets 7—13-flowered. E. 
A. occidentalis molle Scribn. 
OO. ies puberulent; spike long and not dense. E. (A. elmeri.) 
A. lanceolatum S. & S. ‘ 

NN. Lemma noi hairy. 
Q. Leaves smooth beneath, pubescent above. W. E. 
A. repens Beauv. (Couch-grass) 
QQ. Leaves rough on both sides. 
R. Spikelets 4—7-flowered. (See MM.) 
RR. Spikelets 7—13-flowered. W.E. (A. smithii.) 
A. occidentalis Scribn.. (Blue-joint) 

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