Brewer and Watson in the Botany of California list four species and one variety of the genus Rhamnus in California as follows: Rhamnus alnifolia, R. crocea, R. californica and var. tomentella and R. Purshiana. Jepson in his Flora of Western Middle California lists three species and two varieties, the only addition to that of the flora of California being the variety ilicifolia. Trelease in his revision of North American Rhamnus records the following species and three varieties of Rhamnus of Western United States: Rhamnus crocea Nutt and var. pilosa, R. alnifolia, R. Purshiana, R. Californica var. tomentella and var. rubra. Coulter lists two of the Pacific Coast species in Western Texas, the R. Purshiana and R. californica.
Proceedings of the Iowa Academy of Science
©1922 Iowa Academy of Science, Inc.
Pammel, L. H.
"The Species of Rhamnus in Southwestern United States and the Pacific Coast and Puccinia Coronata,"
Proceedings of the Iowa Academy of Science, 29(1), 267-270.
Available at: https://scholarworks.uni.edu/pias/vol29/iss1/59