318 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
HERBARIUM SPECIMENS FROM Mexico: 
Hiparco: Sierra de Pachuca, Pringle 9554. 
Mexico: Popocatepetl, open woods, Hitchcock 5980; Rose & Hay 6025, 6036. 
Sierra de las Cruces, cool moist soil, Pringle 4184, 11737. 
Federal District, Bourgeau 912. 
PuEBLA: Pico de Orizaba, Liebmann 723. 
Oaxaca: Sierra de San Felipe, Smith 936. 
73. AGROSTIS L. Sp. Pl. 61. 1753. 
KEY TO THE SPECIES. 
Palea evident, 2-nerved. 
Panicle narrow, contracted, the branches short, as- 
cending, spikelet-bearing from near the base.. 1. A 
Panicle open, the branches spreading, naked at base.. 2. A 
Palea wanting or a small nerveless scale. 
Panicle narrow, rather compact, the branches ascend- 
ing, spikelet-bearing from near the base. 
Glumes awned; lemma bearing a geniculate, 
exserted awn. ..................2000005- 4,A 
Glumes often acuminate but not awned. 
Lemma awned....................0. seeeee 5. A 
Lemma awnless...............20020-20000- 6. A 
Panicle open or somewhat contracted, the branches, 
at least the principal ones, naked on the lower 
part. 
Lemma bearing an exserted awn; glumes 4 mm. 
long, lower branches of panicle 4 or 5 in a 
whorl, slender, spreading, naked below... 9. A. 
Lemma awnless. 
Palea one-fourth to half as long as lemma; 
culms tall and slender; blades flat; 
panicle open but narrow, the branches 
ascending, naked at base, with occa- 
sional short branches intermixed.... 3. A. 
Palea minute or wanting. 
Culms decumbent at base, numerous, 
leafy; panicle open, the slender 
branches branching about the 
middle.......................... 8. A. 
Culms erect. 
Blades long, lax, flat; ligule as 
much as 5 mm. long; culms 
tall and slender; panicle 
open, oblong, the naked por- 
tion of the lower branches as 
much as 4cm, long......... 10. A. 
Blades short, erect; ligule 1 to 3 mm. 
long; panicle very diffuse, 
the branches capillary. 
Plants tufted, without rhizomes, 
usually not over 30 cm. 
high; blades at base of 
plant often numerous and 
Cima, Orcutt 3790. 
. stolonifera. 
. TOset. 
. microphylla. 
. tolucensis. 
. exarata. 
setifolia. 
schiedeana. 
perennans. 
schaffnert. 
