The Phytogeography of Nebraska; I. General Survey (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated.1898 Excerpt: ... CHAPTER IV. THE ECOLOGICAL AND BIOLOGICAL RELATIONS OF THE NATURAL GROUPS. Habitat groups.--When species are looked at from the point of view of phylogeny and taxonomy, they are classified in the several groups of the natural system; when looked at from the point of view of the effect of habitat and of environment upon the plant-body, they are divided into vegetation forms; when considered with reference to the habitats in which they occur, they are arranged in habitat groups. All of these are groups of species. When we look at the floral covering and attempt to distinguish its constituent parts, we find them set off in formations. A formation is a piece of the floral covering, not a group of species. A habitat group is a group of species, which are subject to similar physical conditions, and frequent like habitats. While the term habitat group has been restricted to a group of species put together by reason of occurrence in like habitats, it might be applied to a different conception, namely, to the aggregate of individuals found within a certain habitat. The latter application of the term would be more natural, but in such case the conception of a habitat group would correspond closely to that of a formation, and the two terms would be synonyms. In dealing with a flora phytogeographically, it is desirable to regard it from several standpoints. Since the conception of the habitat group here adopted permits us to consider the flora from an additional point of view, and to express the part played by the various species to better advantage, it has been preferred. Habitat groups, whether looked at from the one standpoint or the other, are determined primarily with reference to certain physical factors. By far the most important of these is the water content of...