NORTH AMERICAN FLORA. 279 
met with; and farther south the peculiar forms increase. On 
the other hand, it is interesting to note how many Old-World 
species extend their range southward even to lat. 86° or 35°. 
I have not seen the Rocky Mountains in the Dominion ; 
but I apprehend that the aspect and character of the forest is 
Canadian, is mainly coniferous, and composed of very few 
species. Oaks and other cupuliferous trees, which give char- 
acter to the Atlantic forest, are entirely wanting, until the 
southern confines of the region are reached in Colorado and 
New Mexico, and there they are few and small. In these 
southern parts there is a lesser amount of forest, but a much 
greater diversity of genera and species; of which the most 
notable are the Pines of the Mexican-plateau type. 
The Rocky Mountains and the coast ranges on the Pacific 
side so nearly approach in British America that their forests 
merge, and the eastern types are gradually replaced by the 
more peculiar western. But in the United States a broad, 
arid and treeless, and even truly desert region is interposed. 
This has its greatest breadth and is best known where it is 
traversed by the Central Pacific Railroad. It is an immense 
plain between the Rocky Mountains and the Sierra Nevada, 
largely a basin with no outlet to the sea, covered with Sage- 
brush (i. e. peculiar species of Artemisia) and other subsaline 
vegetation, all of grayish hue; traversed, mostly north and 
south, by chains of mountains, which seem to be more bare 
than the plains, but which hold in their recesses a considerable 
amount of forest and of other vegetation, mostly of Rocky 
Mountains types. 
Desolate and desert as this region appears, it is far from 
uninteresting to the botanist; but I must not stop to show 
how. Yet even the ardent botanist feels a sense of relief and 
exultation when, as he reaches the Sierra Nevada, he passes 
abruptly into perhaps the noblest coniferous forest in the 
world, —a forest which stretches along this range and its 
northern continuation, and along the less elevated ranges 
which border the Pacific coast, from the southern part of Cali- 
fornia to Alaska. 
So much has been said about this forest, about the two 
