Cirsium loncholepis is a rare species of thistle known by the common name La Graciosa thistle. It is endemic to California, where it is known from about 15 remaining occurrences in wetlands where southwestern San Luis Obispo County borders northwestern Santa Barbara County. It grows in coastal scrub and sand dunes, marshes, and moist grasslands in the watersheds of local rivers, including the Santa Maria River. It is a federally listed endangered species.