San Francisco Bay spineflower (Chorizanthe cuspidata var. cuspidata)

In the last newsletter, we discussed the extensive coastal dune communities that were present in San Francisco’s not too distant past. The coastal dune systems along the west coast of the United States have suffered terribly at the hands of humans. Coastal and river sand mining, residential and road development, invasive exotics, river damming and water diversion projects, and oil exploration have resulted in the loss and degradation of these diverse and highly sensitive plant communities. The impact of humans on the coastal dune communities has been perhaps even more devastating than that experienced by coastal wetlands.

What remains are eight major dune areas from San Francisco northward (San Francisco, Point Reyes, Dillon Beach, Bodega Beach, Point Arena, Fort Bragg, Humboldt Bay, and Crescent City) and five to the south (Monterey, Morro Bay, Nipomo Dunes, Los Angeles, and San Diego). Of these, the dunes at Humboldt Bay, Point Reyes, Morro Bay, and parts of the Nipomo/Santa Maria complex are the least disturbed. Dunes at Monterey and San Diego Bay have been used by the military. The remaining seven areas have been highly impacted and altered.

In San Francisco, remnants of coastal dunes can still be seen at Crissy Field, Baker Beach, Lobos Creek, Point Lobos, Fort Funston, Lake Merced, Grandview Park, Hawk Hill, Yerba Buena Island, and along Ocean Beach. The Golden Gate National Recreation Area and the National Park Service have undertaken an ambitious program to restore the dunes at Baker Beach, Lobos Creek, and Crissy Field. San Francisco Recreation and Park Department is in the process of acquiring Hawk Hill and will restore natives there and at Lake Merced.

A total of 14 rare plants occur or once occurred on San Francisco’s dunes. These include compact cobwebby thistle (Cirsium occidentale var. compactum), round-headed Chinese houses (Collinsia corymbosa), San Francisco wallflower (Erysimum franciscanum), dune gilia (Gilia capitata ssp. chamissonis), many- stemmed gilia (Gilia millefoliata), San Francisco gumplant (Grindelia hirsutula var. maritima), short-leaved evax (Hesperevax sparsiflora var. brevifolia), wedge-leaved horkelia (Horkelia cuneata ssp. sericea), beach layia (Layia carnosa), San Francisco lessingia (Lessingia germanorum), large-flowered linanthus (Linanthus grandiflorus), curly-leaved monardella (Monardella undulata), San Francisco campion (Silene verecunda ssp. verecunda) and San Francisco Bay spineflower (Chorizanthe cuspidata var. cuspidata).

San Francisco Bay spineflower is a prostrate member of the buckwheat family (Polygonaceae). You might be more familiar with better known members of this family, the buckwheats (Eriogonum spp.). San Francisco Bay spineflower grows four to eight inches high and produces a basal rosette of oblanceolate leaves one to two inches long. The branching inflorescences of capitate or headlike clusters of flowers have a pair of opposite bracts that look very much like the basal leaves. Flowers consist of a white to rose petalloid calyx inserted into a pinkish involucral tube. Flowers are about an eighth of an inch long and develop from April through July.

San Francisco Bay spineflower, like many members of the genus Chorizanthe, seems to thrive on otherwise barren, disturbed sites on loose mineral soils. It has been found in coastal prairie, coastal dune, coastal scrub, and coastal bluff scrub habitats. It occurs in Sonoma, Marin, San Francisco, San Mateo, and possibly Santa Clara counties; it is believed to have been extirpated in Alameda County. In San Francisco, the variety occurs in several different populations at the Presidio and Fort Funston. It is especially abundant on the dunes in the Lobos Creek valley where the National Park Service has restored ten acres of native dune scrub habitat. Elsewhere on the Peninsula, San Francisco Bay spineflower has been reported from the Lake Merced area, Colma Canyon, and the vicinity of Pacifica.

San Francisco Bay spineflower is currently on the CNPS List 1B: 2-2-3. This status indicates that the variety is rare, threatened or endangered in California, is distributed in a limited number of occurrences, is endangered in a portion of its range, and is endemic to California. Although the variety has no formal state or federal status it is considered a special plant by the California Department of Fish and Game. As such, all impacts must be addressed under the California Environmental Quality Act. San Francisco campion was formerly considered a Category 2 Candidate for listing as endangered or threatened by the United States Fish and Wildlife Service (USFWS). As of February 28, 1996, the USFWS ceased to maintain their list of Category 2 and Category 3 Candidate species, so the San Francisco Bay spineflower is now considered a species of special concern.