242 CONTRIBUTIONS FROM THE NATIONAL 
Spikelets not over 4 mm. 
long. 
First glume more than 
three-fourths the 
length of the 
spikelets, these 4 
mm. long, green 
First glume half to two- 
thirds the length 
of the spikelets, 
these not over 
3.3 mm. long, 
commonly red- 
dish brown..... 
Plants perennial. 
Spikelets short-pediceled along one side of the ra- 
chises, forming spike-like racemes. 
First glume nearly as long as the glabrous ob- 
tuse spikelets... .- weeeee 
First glume much shorter than the spikelets. 
Spikelets hispid and with two crateri- 
form glands on the sterile lemma. 
Spikelets not over 2 mm. long; 
blades not over 4 cm. long... 
Spikelets 3.6 mm. long; blades 4 to 
Spikelets glabrous. 
Blades lanceolate; glumes strongly 
carinate..........-......--. 
Blades linear, often elongated; 
glumes not carinate. 
Spikelets not over 1.5 mm. long. 
Spikelets pointed, not ex- 
panded at maturity by 
an enlarged sterile 
Spikelets blunt, expanded 
at maturity by the en- 
larged sterile palea. 
Rachis bearing slender 
bristles; nodes vil- 
Rachis without bristles; 
nodes glabrous... ... 
Spikelets 2.5 mm. or more long. 
Fruit smooth; axis slender, 
pilose. . . 
Fruit transversely rugose; 
axis flattened,  gla- 
brous. 
Nodes bearded........... 
HERBARIUM. 
12. P. pampinosum. 
ll. P. hirticaule. 
. 55. P. obtusum. 
34. P. pulchellum. 
35. P. biglandulare. 
33. P. frondescens. 
29. P. polygonatum. 
30. P. pilosum. 
31. P. larum. 
. 28. P. longum. 
4. P. barbinode. 
