Abstract
It is of common knowledge, derived from even limited field observation, that color in the petals of many of our native flowers is quite variable. Where these variations seem constant, and are accompanied by other characters, taxonomists use color as one of the bases of species differentiation. On the other hand, some species, such as Phlox divaricata, treated in this paper, show gradations in floral color from pure white through blue and lavender to pink; these variations are evidently unaccompanied by other constant characters which might indicate racial differences.