Fountain Thistle

Cirsium fontinale var. fontinale

Fountain thistle is a California endangered plant species, which means that killing or possessing the plant is prohibited by the California Endangered Species Act (CESA). Fountain thistle is also listed as endangered under the federal Endangered Species Act. Fountain thistle is an annual herb in the sunflower family (Asteraceae) that blooms from May to October with white flower heads. It grows 11 to 24 inches tall on serpentine soils in San Mateo County. Its habitat is limited to seeps and streams in chaparral, valley, and foothill grasslands. Pollinators are important for fountain thistle seed production, and the yellow-faced bumblebee (Bombus vosnesenskii) has been reported as a frequent visitor to flower heads.

According the California Natural Diversity Database, there are five historical occurrences of fountain thistle, but one of the occurrences is presumed to be extirpated. The largest known population is at the Crystal Springs Reservoir managed by the San Francisco Public Utilities Commission (SFPUC). The Improvements to Crystal Springs Reservoir completed in 2013 more than doubled the size of the spillway, eliminating 0.30 acre of fountain thistle habitat. A mitigation and monitoring plan for the species began in 2016. The goals of the plan are to improve the remaining fountain thistle habitat and establish two new populations.

Any loss of fountain thistle habitat is significant because of its limited range and restricted habitat preferences. Research into the reasons behind fountain thistle’s restricted environmental preferences could aid in restoration efforts. The 5-Year Review complied by the United State Fish and Wildlife Service recommends studying fountain thistle propagation methods for future out-plantings.

CDFW may issue permits for fountain thistle pursuant to CESA, and you can learn more about California laws protecting fountain thistle and other California native plants on the CDFW website. Fountain thistle occurs in CDFW's Bay Delta Region. More information is also available from the U.S. Fish and Wildlife Service Species Profile for fountain thistle.

Updated 6/29/2017

white petaled thistle flower head
Cirsium fontinale var. fontinale, Photo © Neal Kramer
black and white line drawing of Cirsium fontinale - click to open in new window
Cirsium fontinale var. fontinale, CDFW illustration by Mary Ann Showers. Click to enlarge.