Factors of the habitat are very imperfectly understood.
Tue HabitatThe term habitat, in its widest sense, includes all the factors of the environment which affect a plant or a plant community, though the term is frequently used to signify only some of these factors.
Most of them are natives of the Old World, and chiefly of its eastern division, but several inhabit the western portion of North America, and one, C. githagineus (of which there seem to be at least two local races), is an especial native of the deserts, or their borders, of Arabia and North Africa, extending even to some of the Canary Islands - a singular modification in the habitat of a form which one would be apt to associate exclusively with forest trees, and especially conifers.