Date of this Version
AN ILLUSTRATED GUIDE FOR PLANT-LOVERS AND PLANT-USERS WITH TWENTY-FIVE PLATES IN COLOR AND TWENTY-TWO PLATES IN BLACK AND WHITE
The present book is an endeavor to present the materials of the Rocky Mountain flora in preliminary form from the standpoint of the experimental ecologist. The latter is concerned primarily with the relationships of "species" and their subdivisions as an organic expression or measure of habitat differences, and of the competitive relations of the various formations. Whatever the taxonomic value of the numerous segregates of the last decade or two, the fact that the binomial form conceals the relationship to the original species, and that the segregate itself is based not at all or only slightly upon habitat relations, makes them of little value to the ecologist. This condition is emphasized by the extreme difficulty of their field determination and recognition. No attempt has been made to pass upon the merits of segregates as such, but similarity and relationship have been taken as determining the units used, with the conviction that the differences will appear all the more clearly when habitat and formation have been thoroughly studied experimentally. To the ecologist, ifr seems certain that such experimental analysis of the unit must carry with it the regular use of the trinomial, leaving binomials only for the unit as a whole, whether capable of analysis or not. In spite of some quantitative study of the origin of new forms by adaptation to the habitat, and some statistical study of variation from habitat to habitat, during the past decade, the authors recognize clearly the tentative nature of the units employed. While the latter agree in the main with the "species" of Linne, and of Gray and the earlier American botanists, the initial test of continuous variation or discontinuous adaptation has merged a considerable number of these, and must be expected to unite still more. The questions of a species, its inherited constancy, etc., have not been raised, as this seems futile without continued experiment. The units employed may be "species" or not, but at present they mean nothing more than that the individuals or groups of individuals in a unit are more nearly related to each other than to any other group. In fact, whenever the curve of variation is continuous, it is felt that a unit is indicated, regardless of the height of the modes.