NORTH AMERICA. 



63 



form the transition to the Flora of the United States. The Ameri- 

 can elm may almost be called a Canadian tree, for it is in the north 

 that this most magnificent tree of the temperate zone attains its finest 

 proportion. 



The region of the United States may be considered botanically to 

 include the whole central tract of North America, from about 50° to 

 25° N. lat. This region consists of two forests, the Eastern and 

 Western, and one unwooded tract. The eastern part was originally 

 occupied by an unbroken forest, extending from Hudson's Bay to 

 the Mexican Gulf, and westward far beyond the Mississippi, though 

 here confined to tlie banks of the rivers. The only encroachments 

 by prairies or unwooded tracts, are in Illinois, Indiana, and also in 

 Ohio, in the north, and in Mississippi and Alabama, in the south. 

 This vast forest is composed of 140 kinds of trees, of which 

 more than eighty reach the height of sixty feet and upwards. The most characteristic forms 

 are the hickories, tupelos, lyriodendron or tuHp-tree, the taxodium or American cypress, the 

 locust, the coffee-tree, and the negundo. It is further remarkable for possessing numerous 

 oaks, ashes, and pines, several magnolias, a gordonia (loblolly bay), a plane (sycamore or but- 

 tonwood), a liquidambar, a tree andromeda, two walnuts, three tilias, the red bay, the hack- 

 berry, &c. Within this forest are found only such shrubs and herbaceous plants as require more 

 or less protection from the sun. This has been the principal cause of our cukivated grounds 

 bemg so exclusively occupied by plants introduced from abroad. 



Elm. 



Tulip Tree. 



Loblolly Bay. 



Liquidambar. Tree Andromeda. 



In the prairie region the grasses have usurped the domain of the trees and shrubs ; the 

 northern parts present a strong analogy to the Tartarian steppes, not only in their physical 

 aspect and numerous salines, but in their vegetation, which is gay with a profusion of flowering 

 plants. In the south-western portion the grasses are very thinly scat- 

 tered, and towards the Rocky Mountains the vegetation is so scanty, 

 that the name of desert has been given to an extensive tract ; but 

 there is no part destitute of rivers in all seasons, or where the cactuses 

 and yuccas may not be occasionally met with, or even some cucurbi- 

 taceous plants and grape-vines spreading over the sands. 



The western forest seems to be less extensive than the eastern, and 

 the species appear to be less numerous, but among them are some 

 of gigantic dimensions. Spruces in the north, pines, maples, oaks, 

 and poplars in the middle, and pines in the south, are the prevaihng 

 growth. 



We will suppose, that we have arrived at the frontier of the British possessions, where the 

 sugar maple (Jlcer saccharinum) pours forth its saccharine juice at the first arrival of warm 

 weather, even before the snows have had time to melt ; the azalias add their gay and fragrant 

 blossoms to the beauty of the opening summer, while the autumn is closed by the appearance 

 of many kind of asters, which stud the woods and meadows with their white or violet starry 

 flower-heads. At this point wheat and other kinds of grain, with maize, are successfully culti- 

 vated, and even tob^icco, such is the degree of summer-heat, is a common field-crop. 



In the United States the great features of the North American Flora are at length assumed. 



Prickly Pear. 



