By Fred Roberts, Rare Plant Botanist
Cliff spurge, a member of the spurge family (Euphorbiaceae), is a 1.0 to 1.5 meter (3-4.5 feet) tall shrub that has rubbery, soft stems, and a tangled rounded or somewhat sprawling form. The branches are naked in the dry season but have leaves with a rounded to oval outline in the spring, that are folded upward and mostly less than 1.5 cm long.
Like all members of the genus, cliff spurge has a unique flower-like inflorescence at the tip of the branches called a cyathium.
The cyathium (above) consists of a 2-3 mm tall bell-shaped involucre (fused bracts) and a central stalked female flower surrounded by 30-40 male flowers. The central female flower develops the characteristic three-lobed capsule of the spurge family that appears to hang like a club from the flower. There are five white appendages that look like petals, each with a maroon, sometimes yellow-margined gland at the base. The leaves and branches exude a milky acrid sap when ruptured or cut, which can be a little messy if pressing the plant. Cliff spurge is not likely to be confused with any other native shrub in San Diego County.
Cliff spurge is found mostly along the immediate coast in coastal bluff scrub along bluff margins and coastal mesas from Corona Del Mar in Orange County south into Baja California, Mexico, where it is widespread, and a few outposts along the Gulf of California coast of Sonora. It also occurs on Santa Cruz, Santa Catalina, and San Clemente Islands. An odd disjunct site is also known at White Water Canyon in the Coachella Valley of Riverside County. This far inland site is hardly the only inland site where this plant occurs. In central Baja California’s Vizcaíno Desert, cliff spurge is a common desert shrub right across the peninsula from the Pacific Ocean to the Gulf of California and found at elevations over 400 meters (1,300 feet).
In San Diego County, cliff spurge is somewhat spotty, found primarily along sea bluffs at Carlsbad, Del Mar, Torrey Pines, Border Fields, and especially Point Loma. In extreme southern San Diego County, a cluster of sites is also found along the western margins of Otay Mesa about 10 kilometers (about 6 miles) inland. In our area, the plant is found from sea level to about 160 meters (520 feet) elevation.
The Type specimen has been housed at the Royal Botanic Gardens, Kew in England for about 180 years. If you know anything about the trials that specimens went through to get from a hillside to an herbarium cabinet in the 1700s and 1800s, it is a wonder any specimens actually made it to a museum. This collection was obtained “between San Diego and San Quintin”, Mexico, by Richard Brinsley Hinds, a naturalist and a Royal Navy surgeon assigned to the HMS Sulphur as it conducted a hydrographic expedition.
The collection is sometimes attributed to the year 1841 as indicated in the Kew database. However, Hinds most likely came across the plant in the fall of 1839. A passage written in the 1844 paper The Botany of the Voyage of the H.M.S. Sulphur, states “we had the good fortune to touch rapidly at several places on the coast of Lower, or New California, during October and November 1839.” The HMS Sulphur proceeded south along the western coast of Mexico from there, and evidently struck westward across the Pacific from San Blas, Mexico, on December 21, 1939. The H.M.S. Sulphur would later gain some fame for its participation in the first Opium War in 1840 and 1841 on the coast of China. A little adventure never stops a good botanist. Hinds continued to collect plants even as he may have had to patch up a few sailors along the way. He was collecting plants at Hong Kong in January and February 1841 just before heading home to England.
The Consortium of California Herbaria credits Daniel Cleveland with the first definite collection of cliff spurge at San Diego about thirty years after Hinds passed through the region, in April 1875. Over the next thirty-five years (1875-1910) other collectors contributing to the knowledge of cliff spurge included Marcus E. Jones, C.G. Pringle, John Lemmon, Katherine and Townsend Brandegee, Helen A. Sheldon, LeRoy Abrams, and N.K. Most of these early collections were made on Point Loma. The species is well represented in California herbaria today.
The 1960s, 1970s, and 1980s were a time of furious coastal development and expansion of recreational activities along the California coast, especially in Los Angeles, Orange, and San Diego Counties. With its mostly narrow coastal distribution and preference for seaside bluffs, a favored location for high-end residential and commercial development, large and “showy” cliff spurge earned a slot in the earliest California Native Plant Society’s Rare Plant Inventory, published in 1974, under Appendix II, plants not rare but mostly of limited distribution (if you are unfamiliar with the early CNPS Rare Plant Inventories, they are posted individually on the CNPS website at the bottom of the CNPS Inventory of Rare Plants page. That original 1974 edition looks primitive compared to the later printed versions and positively antiquated by the digital form).
Evidently, there was some disagreement as to how rare or threatened cliff spurge really was. In the 1980 edition of the Inventory, it earned only a “Considered but Rejected” tag but by the 3rd edition of the Inventory in 1984, cliff spurge found its home as a CNPS List 2 species and it has remained there ever since. Cliff spurge is not a covered species under the San Diego Multiple Species Conservation Plan (MSCP) but it is a covered species under the City of Carlsbad Habitat Management Plan, the only element of the north county MHCP yet completed.