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. 36° 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 cupulif erous 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 



