||For many years I have lived on the prairie, where I became familiar with the grasses. Each spring I have been delighted with their renewal of growth-in watching the brown landscape of rolling hills become carpeted with green. Year after year, with the progress of the season, I have seen the changing aspects, which, with the coming of autumn, end in the wonderful coloration of the prairie grasses. But the prairie as a whole has seemed a somewhat elusive thing, difficult to visualize, not easy to describe, indefinite and extremely variable in its composition. This vagueness of understanding, I believe, has been shared by other students of prairie. A careful survey of
the literature reveals scarcely a. single contribution that gives a clear idea of the structure of the vegetation, i.e., what the dominant species are and why they are dominant; what patterns or types of grassland occur in prairie; where they occur; their relative importance; and to what degree the various species intermingle to form them.