For several years I have been engaged, with the assistance of my students, in the study of morphological variation in various angiosperm genera. We have utilized a series of “numerical” techniques in the belief that we thereby attained a greater degree of accuracy and objectiveness that is possible by more conventional techniques. The present paper is an account of studies in three genera, Mimulus, Valeriana, and Geranium. These studies were carried out during the summer of 1961 at the Rocky Mountain Biological Laboratory at Gothic, Gunnison County, Colorado, and most of the plant samples utilized were obtained in the vicinity of the Laboratory, in the Upper East River Basin, at elevations in the neighborhood of 9500′.