Fountain Thistle

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Fountain Thistle

Cirsium fontinale var. fontinale

ListedFebruary 3, 1995
FamilyCompositae (Asteraceae)
DescriptionPerennial with several stout, reddish stems.
HabitatPerpetually moist clay openings in riparian or serpentine chaparral.
ThreatsUrbanization, alteration of local hydrology, dam construction, highway construction, roadside maintenance, competition with non-native plant species, garbage dumping.


Fountain thistle, Cirsium fontinale var. fontinale, is an herbaceous perennial of the aster family (Compositae or Asteraceae) with several stout, erect reddish stems 1-2 ft (30.5-61.0 cm) high. The basal leaves are 4-8 in (10.2-20.4 cm) long with spine-tipped lobes; the leaves on the stems are smaller. The flowers are dull white to pinkish, becoming brown with age. The egg-shaped, recurved bracts beneath the flower head of fountain thistle distinguish it from the most similar thistle in the area, brownie thistle. The nearest relative of C. fontinale var. fontinale is C. fontinale var. obispoense, found further south, in San Luis Obispo County. The related Mt. Hamilton thistle, which grows in serpentine seeps like C. fontinale var. fontinale and C. fontinale var. obispoense, is found in Alameda, Santa Clara, and Stanislaus Counties.

Fountain thistle is a perennial, flowering from June to October. It is thought to be pollinated by bees. Seed production may be quite low although seedlings have been observed. The species may hybridize with C. quercetorum.


Fountain thistle is restricted to perpetually moist clay openings in riparian or serpentine chaparral between approximately 300 and 600 ft (91.4 and 182.8 m) in elevation. Associated rare species include federally listed Marin dwarf-flax and species of concern fragrant fritillary, San Francisco wallflower, and Crystal Springs lessingia.


Historically, fountain thistle may have occurred in both San Mateo and Santa Clara Counties although the Santa Clara County location may be erroneous. The species is now found in only three locations in San Mateo County. One population occurs east of Crystal Springs Reservoir, on both sides of Interstate 280. This location includes three of the five populations of fountain thistle listed in the California Natural Diversity Database. All of the plants in this area may be part of one large population that was originally scattered throughout perennial drainages along the eastern edge of Crystal Springs Lake. A second population occurs 6 mi (9.7 km) to the south in the Triangle area, a triangular piece of land west of Edgewood County Park that is bounded by Interstate 280 to the east, Edgewood Road on the north, and Canada Road on the west. The third location is in Edgewood County Park where a single plant was found in 1987. In 1992, one plant remained in this location. No plants were seen at the location in 1996.

Survey information suggests that the Crystal Springs Reservoir location contains approximately 5,000 plants, and the Triangle population 100-200 plants. The Edgewood Park population consisted of a single plant, but recently surveys have not found any plants in the location. It is felt that the favorable habitat and the presence of a viable population of fountain thistle within 1 mi (1.6 km) of the site provide a favorable long-term outlook for the remaining of the species.


One population of fountain thistle was reported in Santa Clara County, but the site is thought to have been destroyed by urbanization or may be erroneous. Decline of populations in the Crystal Springs region of San Mateo County has been attributed to destruction of habitat from urbanization, alteration of local hydrology, dam construction in the nineteenth century and highway construction. The locality suffered negative impacts from construction of an interchange between Interstate 280 and Highway 92. Some seeps were incidentally created in the process of construction and may provide habitat for C. fontinale var. fontinale. The available information is insufficient to evaluate whether the seeps and drainages in question supported C. fontinale var. fontinale before construction or were colonized as a result of the project.

Three remaining locations of fountain thistle are in San Mateo County. It is threatened by proposed recreational development, roadside maintenance, competition with non-native plant species, and garbage dumping. The location with the most plants is to the east of Crystal Springs Reservoir and north of State Highway 92, along both sides of Interstate 280. It occurs partly on San Francisco Water Department land and partly on a California Department of Transportation right-of-way. Given its proximity to the roadside, it is likely to be affected by any highway projects in the area as well as by highway maintenance. Planned major realignments of Highway 92 were scaled back in order not to impact serpentine grassland. A smaller project to widen Highway 92 east of the reservoir causeway was dropped. Provisions for the removal of water from the increased road surface may adversely affect some of the plants. The California Department of Transportation (CalTrans) is aware of the plant locations and vulnerability.

The proposed construction of multi-use recreational trails on San Francisco Water Department land may present an additional threat to plants in the Crystal Springs area as could associated increased public access. Construction of trails would be done by San Mateo County pending an easement. Trail construction has the potential to threaten the plants through direct destruction of habitat or through modification of hydrologic regimes. Because fountain thistle is dependent upon seeps and springs to provide abundant soil moisture, any disruption in the flow of water would threaten the plants. Trails and their use may also facilitate dispersal of invasive non-native species, an indirect effect more difficult to control.

Non-native plants such as pampas grass have established near the fountain thistle in the Crystal Springs Reservoir area and threaten several sub-populations. Garden debris dumped from households located on the ridge above the plants covers plants and renders the habitat unsuitable for plant establishment and growth.

Fountain thistle may also be threatened by seed predation from beetle larvae. Seedhead weevils introduced for biocontrol of yellow star thistle and other thistles may use rare native thistles such as fountain thistle as well. Further, because there are only two known extant populations of fountain thistle (Crystal Springs Reservoir and the Triangle) and because these populations occur in relatively close proximity to each other, the species may be at risk of extinction from random events or from natural catastrophes.

Conservation and Recovery

The Crystal Springs Reservoir population of fountain thistle is threatened by roadside maintenance. However, authorities are aware of the rare plants in this area, and the maintenance division submits spraying plans for internal environmental review before spraying in the area where plants are known to occur. Personnel of CalTrans and the San Francisco Water Department have considered the removal of pampas grass to benefit the species. The San Francisco Water Department conducted a small removal effort in June of 1997, and CalTrans planned a similar operation. A general management plan for the San Francisco Water Department lands is pending.


U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121


U.S. Fish and Wildlife Service. 1998. "Recovery Plan for Serpentine Soil Species of the San Francisco Bay Area." U.S. Fish and Wildlife Service, Portland.

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Fountain Thistle

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