California Larkspur (Delphinium californicum)

Always a hit in any springtime garden are the larkspurs. Most noted for their tall spikes of deep blue, white, or red flowers with the characteristic spur, larkspurs belong to the Ranunculaceae, or the buttercup family, well-known for its garden ornamentals. Other members of this family, comprised of 50 genera and 1,800 species, include the buttercups (Ranunculus), anemones (Anemone), columbine (Aquilegia), clematis or bower vine (Clematis), hellebore (Helleborus), and meadow-rue (Thalictrum).

But there is oh so much more to the larkspurs than what we know from our local garden center. Larkspurs are perennial herbs that develop from a caudex (the persistent and often woody base of an herbaceous perennial). They occur throughout the northern hemisphere in the Arctic, temperate, and subtropical regions, extending south of the equator into the mountains of Africa. All plant parts of larkspurs contain the compound delphinine, a poisonous alkaloid that can cause vomiting and even death in mammals. Across the western United States, larkspur, especially tall larkspur (Delphinium bareyi), is a significant cause of fatal poisoning in cattle.

The scientific name of the genus is derived from the Greek delphinion and the Latin delphinus, meaning dolphin, presumably for the resemblance of the flowers to the stylized images of the marine mammals. Worldwide, there are some 300 species of delphiniums, and the Flora of North America lists 61 species (85 taxa). California supports 58 native taxa, 20 of which are endemic to the state, which means that they occur nowhere else. Three of our delphiniums are on the federal endangered species list, and a fourth is listed as rare by the State of California; 15 others are considered worthy of listing as rare under the California Endangered Species Act.

There are two subspecies of Delphinium californicum, and they overlap geographically. Hospital Canyon larkspur (D.c. ssp. interius) is known from just 11 locations in Alameda, Contra Costa, Merced, San Benito, Santa Clara, and San Joaquin counties; it is a CNPS List 1B.2 taxon. The more common California larkspur (D.c. ssp. californicum) has been recorded from Santa Barbara, San Luis Obispo, Monterey, Santa Cruz, Santa Clara, San Mateo, Alameda, San Francisco, Contra Costa, Marin, Sonoma, Napa, and Solano counties. Hospital Canyon larkspur has not been recorded from our chapter area.

California larkspur is a stout perennial growing two to seven feet tall, often having two or more hollow stems developing from a single root system. Leaves are palmate, four to five inches across, and with three to 15 sharply cut lobes. Sepals are lavender and densely puberulent (covered with fine, short hairs). Flowers are lavender to greenish white, developing on 12- to 20-inch-long racemes; flowering occurs April through June. California larkspur occurs in dense chaparral from sea level to 3,000 feet in elevation. Hospital Canyon larkspur, which is distinguished by its greenish-white sepals and glabrous (hairless) upper petals, is restricted to openings in chaparral and wet spots in cismontane woodland.

In our area, California larkspur is presumed still extant on Bayview Hill, where it once occurred among the thickets of hollyleaf cherry (Prunus ilicifolia) (Howell, et al. 1958); a single individual was seen about ten years ago, but its current status has not been documented. Historically, California larkspur was known from Strawberry Hill in Golden Gate Park, and Mission and Potrero hills (Brandegee 1891). Nearby, it has been seen recently at Sharp Park, and is known from Colma Canyon, Romanzoffia Ravine, and Owl Canyon on San Bruno Mountain (McClintock, et al. 1990). It can also be found in the hills and mountains of San Mateo and Santa Cruz counties (Thomas 1961), Montara Mountain, Mount Diablo (Ertter and Bowerman 2002), Mount Hamilton (Sharsmith 1982; Ertter 1997), and Marin County (Howell, et al. 2007).

California larkspur is not listed as rare or endangered under the federal or California endangered species acts, nor has it been assigned any status as a rare species by CNPS. As such, impacts to it receive no protection or review under the California Environmental Quality Act (CEQA). However, in our local chapter area, CNPS has designated it as being locally significant due to its highly restricted distribution.

If you hurry, you might still find this rather spectacular plant still in flower. And if you happen to find it on Bayview Hill, by all means let us know!