Cirsium scariosum var. citrinum
Variety citrinum is the southern California race of Cirsium scariosum. As is the case in other varieties of this complex, taxonomic recognition has been given to local populations, named on the basis of limited samples. After examining specimens gathered from various populations in southern California, I realized that although exemplars of local populations may have distinctive features, there are so many intermediates that recognizing any of the local races becomes arbitrary. Individuals treated as Cirsium loncholepis (from coastal sites bordering the mouth of the Santa Maria River and adjacent regions in San Luis Obispo and Santa Barbara counties) are often indistinguishable from plants of upland populations of the San Emigdio Mountains (Kern and Ventura counties) in the vicinity of the headwaters of the Cuyama River, a tributary of the Santa Maria River. Other individuals from the San Emigdio Mountains cannot be distinguished from plants of other upland and lowland southern California sites ranging south to San Diego County.