38 AMERICAN FERN JOURNAL 
apparently an unpublished species name.* Selaginella 
densa (of which S. Haydeni Hieron. and S. Bourgeauii 
Hieron. are undoubted synonyms) is clearly the nearest 
ally of S. scopulorum and agrees with it closely in habit. 
But S. densa, at least as found in the northern region of 
the Dakotas, Montana, and Wyoming, is a plant readily 
recognized by the conspicuous tufts of very long, slender, 
white, subpilose-serrulate bristles at the ends of the 
branches. In S. scopulorum the terminal awns are not 
only shorter, stiffer, and more nearly straight, but are 
whitish-hyaline from a plainly lutescent base, and they 
are never aggregated in tufts, asin S densa. The blades 
of the foliage leaves are different in the two species also; 
those of 8. densa are obtuse and terminate abruptly in 
a long filiform bristle, while those of S. scopulorum are 
less obtuse, tapering slightly to the awn proper through 
a thick, distinctly lutescent awn-base The sporophylls 
of S. densa, moreover, are conspicuously long-ciliate, 
with oblique hairs; in S. scopulorum the sporophyll 
cilia are very much shorter and less oblique. 
In the territory from Wyoming southward to New 
Mexico there occurs a puzzling series of plants, usually 
referred to S. densa, which need the most critical study. 
A part of this material is probably referable to S. Engel- 
mannt Hieron.,7 which may have to be taken up as a 
subspecies of S. densa. With the accumulation of more 
ample material the writer hopes to be able to discuss 
S. densa and related forms in a later paper, including 
their relationship to typical S. rupestris. 
Selaginella scopulorum is the plant listed by Stand- 
ley,’ upon the writer’s identification, as A. montanensis 
* Not to be confused with S. rupestris ccolumbiana Jones (Bull. Univ. 
from Idaho. This, sO 
Montana, Biolog. Ser., 15: g. 
i manni has not been seen by the writer. 
Flora cf Glacier National Park (Contr. U. 8. Nat. Herb. 22: 235-438. 
pls. 33-52. 1921). 
4 
