1094. Cold and lofty situations are the favourite habitations of most cryptogamic plants of the terrestrial class, especially the Fungi, Algï¾µ, and Mosses ; as also of plants of the class Tetradynamia, and of the Umbellatï¾µ and Syngenesian tribes : whereas, trees and shrubs, ferns, parasitic plants, lilies, and aromatic plants, are most abundant in warm climates; only this is not to be understood merely of geographical climates, because, as we have seen, the physical climate depends upon altitude. In consequence of which, combined with the ridges and directions of the mountains, America and Asia are much colder in the same degrees of northern latitude than Europe. American plants, vegetating at forty-two degrees of northern latitude, will vegetate very well at fifty-two degrees in Europe: the same, or nearly so, may be said of Asia; which, in the former case, is perhaps owing to the immense tracts of woods and marshes covering the surface; and in the latter, to the more elevated and mountainous situation of the country affecting the degree of temperature. So also Africa is much hotter under the tropics than America; because, in the latter, the temperature is lowered by immense chains of mountains traversing the equatorial regions; while in the former it is increased by means of the hot and burning sands that cover the greater part of its surface.
