
1901 | NORTH AMERICAN TREES 237 
This is the ‘‘canoe birch”’ of all travelers in Alaska, and it is the 
common birch tree of the Yukon valley, where it grows spar- 
ingly near the banks of that river in coniferous forests and abun- 
dantly on sunny slopes and hillsides, and extends down the river 
at least as far as the Russian mission, two hundred and thirty- 
three miles above its mouth (M. W. Gorman 7x Uitt.). 
From Betula papyrifera Marsh, which is common in one of its forms in 
southern Alberta, northern Idaho, and Montana, and in the Blue mountain 
region of eastern Washington and Oregon, Betula Alaskana may be distin- 
guished by the close reddish bark of the trunk which is less flexible and does 
not separate as easily into layers as the bark of the eastern canoe birch, by the 
much more verrucose branches, obtuse winter buds, rhomboidal long-pointed 
leaves, stouter fruiting catkins, and by the more habitually acute or acuminate 
central lobe of theirscales. The specimen in Herb. Gray collected by Bourgeau 
in flower on the Saskatchewan was referred by Regel (Bu//. Mosc. 18: 398; 
DC. Prodr. 16 : 164) to his Betula alba, subspecies verrucosa 5 resinifera, 
the Asiatic types of this variety being from Udskoi in eastern Siberia and 
from Transbaical. Specimens of the Alaska tree sent by me to the Herbarium 
of the Imperial Botanic Garden at St. Petersburg were pronounced, however, 
unlike any Asiatic species, and with the slight knowledge of the northern 
Asiatic species of Betula which we possess in this country it does not seem 
safe to follow Regel in uniting North American with Asiatic species. To Mr. 
Gorman I am indebted for very complete specimens of Betula Alaskana 
collected at different points on the Yukon in 1899, and for the first reliable 
information I have been able to obtain in regard to the trees of the Yukon 
valley and their distribution. 
BETULA OCCIDENTALIS Hooker. There are three arborescent 
birches in the region between the eastern base of the Rocky 
mountains in the United States and the shores of Puget sound 
and British Columbia. 
First, Betula papyrifera Marsh, in one of its forms which 
enters this region from the east and is not rare in northwestern 
Nebraska, northern Dakota, Idaho, and Montana, and reaches 
the mountains of eastern Oregon. 
Second, the large tree which grows on the lower Fraser 
river, on the shores and islands of Puget sound, and on Van- 
couver island. This tree has reddish bark which is particu- 
larly noticeable on young plants, pubescent branchlets, acute 
winter-buds, leaves pubescent on the lower surface, and fruiting 
