Alpine and Boreal Floras of Western America. 959 
Species not known from Shasta. 
Arnica .Chamissonis Less. Lonicera involucrata Banks. 
Campanula Scouleri Hook. Polygonum bistortoides Pursh. 
Crepis nana Rich. (= P. bistorta L.). 
Erigeron salsuginosus Rich. Populus tremuloides Michx. 
Gentiana Newberryi Gray. Salix Barclayi Anders. 
Juncus orthophyllus Coville. Saxifraga nivalis L. 
Lonicera conjugialis Kell. Saxifraga punctata L. 
See 
nn, 
f) Boreal Sierra species not known from Shasta or the Cascades. 
table adapted from COVILLE. Ante page 254 sub a.) 
g) Boreal Cascade species not known from Shasta or the Sierra. 
Gaultheria myrsinites Hook. Ribes erythrocarpum. 
Menziesia ferruginea Smith. Ribes lacustre Pir. 
Rubus lasiococcus Gray, Valeriana sitchensis Bong. 
Silene acaulis L. Sorbus occidentalis Wats. 
Rhododendron (Azaleastrum) albi- Spiraea arbuscula. 
florum Hook. Vaccinium microphyllum Reinw. 
The tabulation of the species here presented may serve to illustrate the 
fact, that a circumpolar boreal plant, if it occurs in North America at 
all is usually found over broad areas, Of at widely separated points. 
This principle is supported by the fact that the group of species common to 
all three mountain ranges contain some that are circumpolar while those that 
are common to one, or at most two ranges include not a single circumpolar 
species. Several of these circumpolar species | 
mountains of the Atlantic side of the continent. This indicates that the pre- 
sent boreal flora was at one time diffused over the base level of a large trans- 
verse zone south of the Canadian line; in other words the flora of the north 
in glacial times was far more homogeneous in an east and west direction than 
our present flora. Finally, our two great western mountain systems do not 
show marked isolation, as a group, but each has a well- defined individual 
isolation. Of the species common to the Sierra Nevada, Cascade Mountains 
and Rocky Mountains, nearly one-half are also either Alaskan, or circum- 
polar; while the number of those common to the three ranges and confined 
within them is less than the number confined to the Sierra Nevada alone ;" 
Attention must be called to the glacial meadows of the high Sierras, 
because they are covered with many plants which enter largely into the com- 
position of the flora. The glacial meadows are smooth, level, silky ee 
lying imbedded in the upper forests, on the floors of the valleys, and along 
the broad backs of the main dividing ridges, at & height of about 8000 to 
9500 feet above the sea. They are nearly, $ level, as the lakes whose places 
1) CoviLze, F. V. 1. c. p. 30. 
ı7r 
