1907] Lamson-Scribner,— Notes on Muhlenbergia 21 
other name available for this very well defined species a new one, 
M. umbrosa, is here proposed. 
Torrey thus describes the species closely following Muhlenberg 
in his diagnosis of Agrostis diffusa “Culms erect, much branched, 
diffuse, smooth; stipules lacerate panicle filiform; corolla longer 
than the calyx; awns three times as long as the flower." Torrey 
compares the species with M. tenuiflora from which he says it differs 
"jn being much branched and diffuse, the glumes are also longer and 
narrower and the culms are glabrous at the nodes." 
The type of this species is in Muhlenberg's herbarium in the Acad- 
emy of Natural Sciences of Philadelphia. It has much branched 
culms with numerous filiform panicles and long-awned spikelets. 
No. 205 A. Commons from Delaware and no. 461 B. Fink from Iowa, 
both in the Natl. Herbarium are identical with the type. The general 
aspect of the species is unlike that of either M. foliosa ambigua or 
M. mexicana commutata, both of which have heretofore been referred 
to M. sylvatica by authors. The panicles are more slender, the spike- 
lets are less crowded and are usually pale green or straw-colored, 
never violet or purplish as is usual in those subspecies. 
6a. MUHLENBERGIA UMBROSA attenuata Scribn. n. subsp. Lemmas 
awnless or merely mucronate-pointed. Otherwise as in the species. 
Type, no. 25 E. N. Wilcox from Aurora Co., South Dakota. 
No. 27 J. H. Kellogg from Missouri; no. 8096 E. S. Steele from 
the District of Columbia; no. 523 M. L. Fernald from Maine, 
belong here. The subspecies ranges from Maine to Dakota 
and Nebraska southward to Missouri and Kansas. 
A very careful study of the abundant material classified under 
Muhlenbergia mexicana and M: sylvatica in the National Herbarium, 
has led to the interesting conclusion that both these species present 
awned and awnless forms and that the true M. sylvatica should be 
limited to the Agrostis diffusa of Muhlenberg, a well marked species 
quite distinct from awned forms of M. mexicana or of the restored 
M. foliosa of Trinius. In the case of these latter species it was found 
that every slight variation in habit in plants with awnless spikelets 
could be exactly matched by awned specimens, the presence of the 
awn being the only difference whatever. The natural conclusion 
is that the awnless and awned plants belong to the same species and 
that at best the latter (those with awned spikelets) could only be 
treated as subspecies of the former. It appears also, that Muhlen- 
