As originally described by Helen Sharsmith in 1939 (see her very detailed protologue here), this taxon was named Cirsium campylon and assigned to the rank of species. Sharsmith noted it was found growing in dense colonies on moist, sandy, serpentinite-derived soil at springs or along perennial stream margins...much like its close congener C. fontinale var. fontinale, but with more pronounced terminal nodding of the flowering peduncles, longer involucral bracts, and other distinctions (and, also, not quite as rare). The location in the post here is very near the type locality for C. campylon (which was at the confluence of Adobe & Del Puerto Canyons).

It was later placed as a variety of C. fontinale in Keil & Turner(1992).