A study ot discordant variation in populations of Purshia tridentata, Purshia glandulosa, and Cowania Stansburiana has disclosed that introgressive hybridization can be expected whenever these species come in contact with each other. The introgression is not only of one pure species into that of another, but is also of introgressed populations into other introgressed populations and of pure populations into introgressed populations. Evidence was found showing that in all probability Purshia glandulosa is a stabilized segregant derived from introgressed populations. Evidence was also found and presented to show that introgression is responsible for the recent acquisition of stalked hypanthium glands by many populations of Purshia tridentata .

A root study was undertaken to learn about bitterbrush (Purshia tridentata (Pursh) DC) and cliffrose (Cowania stansburiana torr.) to gain some clues, perhaps, as to the causes of their present distribution. In a period extending from July 1959 to July 1960, twenty-four plants were excavated on six different sites in the Wasatch foothill belt in Utah County, Utah. Root and some soil characteristics were analyzed, described and compared.