SILVA OF NORTH AMERICA. BETULACEA. 
58 
lobe rounded at the narrow apex. The nut is oval, about a sixteenth of an inch long, and nearly as 
wide as its wings.’ 
Betula occidentalis inhabits the banks of streams and lakes in southwestern British Columbia and 
northwestern Washington, and nowhere very common grows probably to its largest size on the alluvial 
banks of the lower Fraser River.’ 
Betula occidentalis is one of the largest of all Birch-trees, and, with the exception of the Cotton- 
wood, it is the largest of the deciduous-leaved trees of northwestern North America. It was discovered 
on the shores of the Straits of Fuca by Dr. John Scouler® between 1825 and 1827. In 1893 this tree 
was introduced into the Arnold Arboretum, where it has grown very rapidly and is perfectly hardy and 
where it already displays the orange-brown bark which best distinguishes it from the Canoe Birch of the 
east. 
1 In the ninth volume of this work published in 1896, while call- 
ing attention to the color of the bark of this tree, I considered it a 
Since the publication of that 
volume I have had an opportunity to see this tree again on Van- 
western form of Betula papyrifera. 
couver Island and to compare the young plants in the Arnold Arbo- 
retum with plants of the Canoe Birch of the same age. These are 
so distinct in their bark, and in the color of the branchlets, which 
on the western tree are ge-b: and bright red-b 
eastern tree, that it is not possible to consider them forms of the 
on the 
same species. 
From Betula papyrifera it can also be distinguished by the shape 
of the leaves, which are broad or rounded or on vigorous shoots 
slightly cordate, not cuneate at the base, and by the shorter and 
broader strobiles, with puberulous scales ciliate on the margins, the 
scales of Betula papyrifera being usually glabrous and destitute of 
marginal hairs, although on specimens which I collected several 
years ago on Prince Edward’s Island the scales are sometimes 
puberulous. 
Betula occidentalis was first d 
mens collected near the Straits of Fuca by Dr. Scouler, although 
ibed by Hooker from the speci- 
with them he united a specimen collected by Douglas inthe interior 
The tree from the Straits of Fuca 
appeared first in the description of Betula occidentalis which was evi- 
west of the Rocky Mountains. 
dently drawn principally from the specimens of that tree and must 
therefore be considered the type of Hooker’s species, while the 
second specimen included in this description appears to be one of 
the forms of Betula papyrifera. 
In the ninth volume of this work (65, t. ccccliii.) the half 
shrubby dark-barked Birch with spreading gracefully drooping 
stems which is common in eastern Washington and Oregon, and 
ranges as far south as Colorado, Utah, and northern California, was 
confounded with Betula occidentalis of Hooker and was described 
and figured under that name. This plant was collected by Nuttall 
on the Sweet Water, one of the branches of the Platte, and was 
first described and figured by him as Betula occidentalis. (See 
Sylva, i. 23, t. 7.) Torrey in Frémont’s Report repeated. this error. 
This same species was also described and figured in King’s Report 
(v. 323, t. 85) as Betula occidentalis by Watson, who repeated his 
error in The Botany of California, and it is this plant which is de- 
scribed and figured as Betula occidentalis in the ninth volume of 
The Silva of North America, where an allusion only is made to the 
true Betula occidentalis of the coast in a note under Betula papyrif- 
era. 
Nuttall found another small Birch in the Rocky Mountain region 
and on the plains of the Columbia which he described and figured 
as Betula rhombifolia in the first volume of his Sylva published in 
1842. This plant, judging by one of Nuttall’s original specimens 
in the Gray Herbarium, is the slender-fruited form of the plant 
described by Nuttall as Betula occidentalis, which is common in east- 
ern Oregon and Washington and ranges eastward into Montana 
and Idaho. If the two forms, which seem to vary only in the thick- 
ness of the aments, really belong to one species this would have to 
bear Nuttall’s name of Betula rhombifolia had not Tausch four 
years earlier than Nuttall used that name for a European species. 
Some of the specimens of the tree called Betula occidentalis by Nut- 
bl to afi 
‘5 
tall and Watson bear a strong tary speci- 
men in the Gray Herbarium of the Asiatic Betula microphylla, Bunge, 
but the evidence of this specimen would hardly seem to warrant the 
adoption of Bunge’s name for our tree, for which I have proposed 
(See Bot. Gazette, xxxi. 239.) 
2 The most eastern place from which I have seen a specimen of 
the name of Betula fontinalis. 
Betula occidentalis is Donald on the Columbia River in British 
Columbia in about longitude 118° west, where it was collected in 
1885 by Mr. John Macoun. 
3 ix, 66. 
EXPLANATION OF THE PLATE. 
Puate DCCXXY. Bertuna OCCIDENTALIS. 
1. A flowering branch, natural size. 
. A fruiting branch, natural size. 
. A scale of a fruiting ament, enlarged. 
2 
3 
4. A scale of a fruiting ament, enlarged. 
5. 
. A nut, enlarged. 
