1900] Fernald, — Rubus idaeus in America 199 
gosus, Maxim.'), and there is little doubt that the relationship of 
_the plants is thus more truly presented than by the forced separation 
of them as specific types. The extreme tendency, as seen in the 
American plant, to variation not only in leaf but in the degree of 
gland development, is sufficient to suggest that Maximowicz may 
be too liberal in his treatment of the glandular plant, for, if in the 
open one can find the glandular form, and near by, in shade, numer- 
ous variations to the glandless state, the recognition of the American 
plant, even as a geographic variety, seems scarcely warranted. 
Nevertheless, whether we regard the two plants as representing 
mere phases of a polymorphous species, A, ZZaeus, or as somewhat 
characteristic geographic varieties — the glandular extreme encour- 
aged by the dry atmosphere of the American continent, the glandless 
one by the moister atmosphere of northern Europe — there is little 
doubt that they are practically one species. And although the round- 
leaved plant of the Green Mountains bears upon its calyx more 
glands than are usual in the European plant, there seems little reason 
to distinguish it as another variety. That the variable American 
plant with glandular calyx should occasionally produce a sport parallel 
with the glandless European var. anomalus is possible, and such 
extreme variations may be looked for with some confidence. 
But, in the case of the Cavendish station, it seems not improbable 
that the plant had the same geographic origin as the colonies in 
northern Europe, for, at the same station, at least one other plant is 
known which is far removed from the broad range of its species. 
There, as already mentioned, is found Arenaria macrophylla, a species 
characteristic of the mountains of our Pacific slope, though occurring 
also at isolated stations on the Great Lakes and in Labrador. The small 
Rubus at Cavendish, then, is associated with a plant, which, with little 
doubt, was established there during the northward march of the veg- 
etation at the close of the Glacial Period ; and it is reasonable to suppose 
that the Rubus, formerly growing in Age regions, was forced 
south by the southward extension of the ice, most of the plants? fol- 
lowing the meridians which pass through northwestern Europe, but a 
few following down this side of the Atlantic ; and now a remnant of 
* Bull. Acad. Sci. St. Petersburg, xvii. (1871), 161. 
* Although this plant ordinarily produces no fertile drupes, according to 
Babington (Jour. Bot. xvi. 85) occasional good seed are formed — probably enough 
to have spread the plant to its few scattered stations. 
