216 Rhodora [SEPTEMBER 
two, and probably three such variants. As in the case of Athyrium 
angustum, the lands about the Gulf of St. Lawrence are a region of 
maximum departure from the ordinary type of the species. 
As in the case of Athyrium Filix-femina, Botrychium virginianum 
var. europaeum undergoes a marked change in passing southward into 
the Californian region and there develops the peculiar variety, Botry- 
chium virginianum var. occidentale. 
Like the Filix-femina group, Botrychium virginianum and its allies 
have a typical boreal distribution, and all tropical forms of this group 
have evidently come from the north. Thus in Mexico we find Botry- 
chium virginianum var. and Botrychium cicutarium. The latter species 
is also in the West Indies, and this or a closely allied species occurs for 
some distance south in the Andes. In Asia, Botrychium lanuginosum, 
considerably more aberrant than any of the forms yet mentioned, 
occurs in the Himalayas, and in southern China, and thence south to 
the hill country of southern India, Ceylon, and the Philippine Islands. 
There is a single species of Botrychium in Africa, and that is said to 
be a close relative of the last mentioned species, and hence a member 
of the Botrychium virginianum group. This is Botrychium chamaeco- 
nium, and it occurs in the mountains of Cameroon. It is the only 
member of the group which is not either strictly boreal, or else in 
tropical mountains with easy access to the north. 
In one respect the Botrychium virginianum group differs in its 
distribution from the Filix-femina group. They present their most 
complicated arrays of forms, not in Asia, but in eastern North Amer- 
ica, and it seems probable that the latter region is the center of dis- 
tribution of this group of plants. 
EXPLANATION OF PLATE 123. 
Figs. 1-2. European specimens of Athyrium Filix-femina (L.) Roth: 
fig. 1, pinnule of var. multidentatum (Déll) Milde, X 24; fig. 2, pinnule of var. 
fissidens (D6ll) Milde, x 5. 
Figs. 3-10. Athyrium asplenioides (Michx.) Desv.: fig. 3, pinna of typical 
form, X 4; fig. 4, pinnule of the same frond, X 5; fig. 5, mature pinnule of f..sub- 
tripinnatum Butters, X 2; fig. 6, base of younger pinnule of the same form, X 5; 
fig. 7, indusium of A. asplenioides, X 124; fig. 8, detail of the margin of a 
portion of the indusium, X 50; fig. 9, sporangium, X 50; fig. 10, spores, X 100. 
Figs. 11-18. Athyrium angustum (Willd.) Presl.: figs. 11 and 12, pinnules 
of fertile and sterile fronds, respectively of the same plant of f. typicum, X 5; 
fig. 13, pinnule of var. rubellum (Gilbert) Butters, X 5; fig. 14 and 15, pinnules 
of the fertile and nearly sterile fronds respectively of var. elatius (Link) 
Butters, X 2; fig. 16, base of younger fertile pinnule of var. elatius, X 5; fig. 17, 
margin of indusium, showing the ordinary type found in A. angustum, X 50; 
fig. 18, spores, X 100. 
