Pe ee 


1917] Butters,— Studies in Ferns — Athyrium 205 
The following specimens approach close = the European form in 
the cutting of the frond, but have no indus 
CALIFORNIA: near summit of Sierra Nevada, Nevada Co., 1873, 
Muller; en south of Donner Pass at 7500 ft., Nevada Co., August 
: A. A. Heller no. 7186; 11500 ft. altitude, Saw Tooth Peak, 
Tulare ‘Goon August 17, 1904, Culbertson 
OrEGON: Union Co., 1878, W. C. Cus 
WASHINGTON: Wenatchie region, ietane 7000 ft., August 1883, 
T. S. Brandegee no. 1222. 
From this study of the Filix-femina group of Athyrium, it appears 
that these ferns follow certain laws of distribution, which have been 
noted often in the case of Phanerogams. Thus we find that the com- 
mon woodland species of eastern North America (A. angustum) either 
reappears in eastern Asia, or is represented there by a very closely 
related species.' This plant, like many others of eastern North 
America ranges northeastward into the region of the Gulf of St. 
Lawrence, and there appears, often in a peculiar form, the variety 
laurentianum2 A very distinct species (A. asplenioides) occurs in 
the southeastern United States, and like so many plants of that 
region, extends northward along the Atlantic as far as southeastern 
New England. 
The common fern of cool temperate Europe on Filix-femina) 
extends well across Asia, occurs in Kamchatka, and reappears in 
Alaska and British Columbia in precisely the same form. There are, 
however, in each of the chief areas occupied by this species, certain 
well marked minor forms peculiar to the respective regions,— in 
Europe the various finely cut forms, especially that commonly known 
as the variety rhaelicum, in the Pacific coast region from Alaska to 
Oregon the variety sitchense. Like a great number of plants of the 
wet western coast, this latter variety reappears at low altitudes on the 
climatically similar west slope of the Selkirk Range. . 
1 The oom corecee aaa the _— of the region of deciduous forests of eastern North 
A ica p eastern Asia, was long ago pointed out by Asa Gray, 
in his classic essay, “‘ Observations upon the Relation of the Japanese Flora to that of North 
America and other Parts of rae northern Temperate Zone.’ Mem. of the Am. Acad. of Arts 

h 
found that a great many of the Leas of that region are similarly aaa: ‘Bei i me 
that it is never safe to assume that a plant of Newfoundland or Gaspé is identical with an ap- 
weg te similar species of the eastern United States, until a detailed study has been made of 
all its technical characters. 
3 Several years ago the author Dointed out (The von of ae neeek } ap ge Ap- 
pendix A. to Howard Palmer * 354. 1914) 

