THE OAK-VEGETATION OF AMERICA. 325 
but disappear altogether in the vast prairies, which extend from the 
westward of those mountains to the Rocky Mountains. In this last 
great mountain-chain, the Oak seems altogether to be wanting, owing - 
principally, perhaps, to the circumstance that, in ascending from the — 
Prairies, its elevation above the ocean at the very base is such, that 
the Oak can no longer exist. The dry continental climate of the Rocky 
. Mountains co-operates probably with equal force in producing this 
deficiency. The Oaks on the western side are different from those on 
the eastern; the only exception being Q. rubra. 
The most important forest Oaks in those Eastern States, which have 
a temperate climate, are Q. coccinea, a tree eighty feet in height, 
reaching as far as Georgia; Q. Prinus, extending from Pennsylvania to - 
Florida ; Q. oliveformis, which occurs on the shores of the river Hudson ; _ 
Q. triloba, nigra, and falcata. : 
Many of the North American forests are known to be very swampy ; 
and such are chiefly formed of three species, namely, Q. Phelios. 
attaining a height of sixty feet, and extending to Florida; Q. Primus 
var. palustris, and Q. palustris, which spreads especially over Pennsyl 
vania. 
The Southern, or so-called Slave States, possessing a warm, temperate 
or subtropical climate, produce, besides the above-mentioned sorts foun 
in the Northern States, a number of peculiar Oaks, amongst which we 
will enumerate in this place Q. macrocarpa, in the States west of the 
Alleghanies; Q. cinerea, a low tree of Virginia and Georgia; and Q. 
virens, the northernmost of the United States evergreen Oaks, attain. 
ing a height of forty to fifty feet, spreading over Virginia, Florida, and 
the Valley of the Mississippi, and being of great value, as the best nava 
timber-tree of the Southern States. In swampy forests from Carolina 
to Florida, is found Q. lyrata; and from Maryland to Florida Q. 
aquatica, having a height of sixty fect. 
As yet the botany of the western coast of the United States and 
California has been but imperfectly explored. We are indebted to Neé, 
Douglas, Coulter, Hartweg, and Fremont for what is known of the 
Oaks of those parts. Q. rubra has already been named as spreading 
over the western side. As peculiar forms must be mentioned Q. agri- 
folia, the leaves of which resemble the Holly; @. Garryana, Q. Dou- 
glasii, Q. densiflora, a magnificent tree, which is remarkably like the — 
Chestnut, and in appearance very foreign from American Oaks, and 
