_ Graminaceae 59 
M. Panicle 15—35 cm. long. W. E. (P. flava for our region. ) 
P. triflora Gileb. (Fowl Meadow-grass) 
MM. Panicle 5—12.5 cm. long. 
N. Ligule of upper leaf 0.5 mm. long; panicle-rays 4—7 in a whorl. E. 
(P. nemoralis of How. Fl.: P. glauca. ) 
P. interior Rydb. 
NN. Ligule of upper leaf 22.5 mm. long; panicle rays I1—5 in a 
whorl. E. P. laxs, Haenke 
GROUP 
A. Lemma-veins with long soft hairs along their lower portion. 
B. Annual. W. E. F. annua L. (Annual Spear-grass) 
BB. Perennial. 
C. Seashore plant. W. F. pachypholis Pip. 
CC. Not a seashore plant. 
D. Ligule of upper leaf 2-3 mm. long; lemma 3-veined, spikelets 5-6 mm. 
long; panicle 2.57.5 cm. long. C. 
P. alpina L. (Mountain Spear-grass) 
DD. Ligule of upper leaf 410 mm. long; lemma 5-veined; spikelets 6—12 
mm. long; panicle 7.5—-12.5 cm. long. E. 
I’. longiligule, Scribn. 
AA. Lemma-veins without long soft hairs, tho often pubescent or hispid. 
E. Lateral veins of the lemma arched, converging above. 
' F. Leaves filiform and rolled up. 
G. Panicle dense. ; 
H. Lemma smooth; leaf-blade smooth. E. 
P. cusickii Vas. 
HH. Lemma scabrous; leaf-blade scabrous. 
I. Glumes both linear-lanceolate and |-veined. E. 
P. subaristata Scribn. 
II. Glumes wider, the lower 1-veined, the upper 3-veined. E. 
P. cottoni Pip. 
GG. Panicle loose. 
J. Flowers of the spikelet close; ligule of upper leaf 4 or more mm. long. 
: P. capillarifolia S. & W. 
JJ. Flowers of the spikelet loose; ligule of the upper leaf 2—3 mm. long. E. 
P. idahoensis Beal 
FF. Leaves wider than filiform, often folded or rolled up. 
K. Lemma glabrous on the back. E. 
P. curtifolia Scribn. 
KK. Lemma hairy or scabrous on the back at least on the veins. 
L. Spikelets almost terete. 
M. Spikelets 45 mm. long; plant 1.5—-3 dm. high, W.C. (Sporo- 
bolus bolanderi.) : 
“P, multnomae Pip. 
MM. Spikelets 6—9 mm. long; plant 3—6 dm. high. W. 
P. alcea Pip. 
LL. Spikelets much flattened. 
N. Spikelets 8—10 mm. long, 4—7-flowered. W. E. (P. helleri.) 
P, nervosa Vas. 
: NN. Spikelets 5—-7 mm. long, 2—4-flowered. 
