206 Rhodora [SEPTEMBER 
The southern extension of A. Filiz-femina into the western United 
States is marked by a peculiar technical variety, as seems often to be 
the case with northern plants which extend south into California and 
the southern Rocky Mountains. 
The Filiz-femina group of the genus Athyrium presents a typical 
case of boreal distribution. Apparently the center of this distribution 
is somewhere in Asia. Christ says of the genus Athyrium in China, 
“The variation of the genus Athyrium in southern China is only 
equalled by that of the same genus in Japan and the Indian Himalaya, 
other countries belonging to the same botanical region... .It is a 
plastic mass which appears to be endlessly modified.’ 
On the other hand the number of species of this genus in North 
America is limited to those just described and the two diplazioid 
species A. acrostichoides and A. angustifolium. ; 
Moreover, as has been pointed out already, the Diplazia of tropical 
America, presumably descendents from the genus Athyrium, though 
very numerous as to species, appear to belong almost wholly to a 
section of the genus which is probably descended from Athyrium 
acrostichoides (Sw.) Diels or some very similar species, while the Asiatic 
A form a mass of species of almost endlessly complicated rela- 
tionshi 
as of f the true Filix-femina group extend south into the tropical — 
mountains in Mexico (A. Martensi and A. Dombei Desv.), and 
rey 

of the Selkirk Range with that of Scandinavia. Evi- 
cose A oomonetiog "that this relationship extends to parts of the flora which cannot be 

- 
ae £, ae 

in rly thn same form nthe olan moat everron forests of British Cains 
Tk of Athy ius ipestre i in th tail f western America,— in this case in # 
tance of th and north-west 
Amarican foes, though in this can thn plant to disocty apne to a ng ea 
& ts. 



: : facts 
ing the flora of that interesting region. See Fernald, at i ba Hoan ooo 
Alpine and Subalpine Plants. Ruopona, ix. 149 (1907) 
The Reappearance itchense 




“variation do genre Atlorn on Chine mii n'a d’égale que celle du méme genre au 
Japon e C'est 


. Christ, H. Les collections de Fougeres 
dei Chine a Museum hiner naturale de Pari Bull, Soc. Bot. de France lii. Mém. i- 
50 (1905). 

