This revision discusses two closely related species of Plagiobothrys (Boraginaceae) found in the southwestern United States and central Chile. One of the two species, P. collinus, is composed of five varieties that range from southern California and western Arizona to central Chile in South America. The following new combinations are proposed: P. collinus var. californicus, P. collinus var. gracilis, P. collinus var. ursinus, and P. collinus var. fulvescens. Detailed keys, synonymy, and descriptions are given for each entity.
Higgins, Larry C.
"A revision of the Echidiocarya section of Plagiobothrys (Boraginaceae),"
Great Basin Naturalist: Vol. 34
, Article 8.
Available at: http://scholarsarchive.byu.edu/gbn/vol34/iss2/8