|Listed||October 7, 1996|
|Description||A herbaceous annual plant.|
|Habitat||Weathered sandstone bluffs within southern maritime chaparral.|
|Threats||Disturbances associated with recreational trampling and habitat changes caused by invasive alien plants.|
Orcutt's spineflower, Chorizanthe orcuttiana, is a low, yellow-flowered annual restricted to sandy soils that belongs to the buckwheat family (Polygonaceae). It is distinguished from other members of the genus by its prostrate form, campanulate three-toothed involucre, and involucral awns that are hooked near the tip.
Orcutt's spineflower is primarily restricted to weathered sandstone bluffs in association with or in microhabitats within southern maritime chaparral. This species is endemic to south-central and southern coastal San Diego County, California.
Orcutt's spineflower, now restricted to just the south-central coast of San Diego County, had historical occurrences in this county in ten locations at Point Loma near San Diego, (including the U.S. Naval Reservation), Del Mar, Kearney Mesa, and Encinitas. Only two populations have been seen in recent years. Fifty to 100 individuals were reported at Torrey Pines State Park in 1987; however, this population has not been relocated in the last several years, possibly due to changing plant species composition and density as result of a 1984 burn. The species was thought to be extinct until a new population was discovered in 1991 at Oak Crest Park in Encinitas. This population, distributed over a very small area of about 43 sq ft (3.8 sq m), numbered fewer than 40 individuals in 1993 and fewer than ten individuals in 1994. The number of individuals varies widely from year to year because the success of germination is highly dependent on rainfall and other climatological factors, which often differ significantly from one year to the next in southern California.
Orcutt's spineflower is confined restricted to exposed sandy soils at two sites in coastal south-central San Diego County. The Torrey Pines State Park site is protected, but this population has not been seen since 1987. The only currently known population is within Oak Crest Park in Encinitas, and these plants are threatened by proposed recreational facilities, as well as by pedestrian trampling and invasive exotic plants. The reduction of the southern maritime chaparral in the park by about one-third will significantly harm the long-term viability of the single surviving Orcutt's spineflower population. This species is very vulnerable to trampling by farm workers and recreationalists because of its small size and preference for open areas, which tend to attract foot traffic through otherwise dense chaparral vegetation. The only known locality could be eliminated in a single event if a particularly large number of people were to walk through and trample the population. Exotic grass and weed species are also serious threats to the remaining Orcutt's spineflower plants. This species is also highly vulnerable to overcollection because of its rarity. Orcutt's spineflower is at considerable risk of extinction from naturally occurring events because of its highly restricted distribution and small population size. Genetic viability can be reduced in small populations, making them less adaptable to changes in the environment; even one natural episode of fire, drought, or severe wind can easily extirpate populations of this kind.
Conservation and Recovery
The only known population of the Orcutt's spineflower is in Oak Crest Park in Encinitas. Although this park is under public ownership, it is heavily used for recreation and this is a severe threat to the endangered spineflower. This critical habitat must be protected, and managed strictly in support of the endangered Orcutt's spineflower. Its population should be monitored, and research undertaken into its biology and habitat needs. It should be propagated in captivity, with the aim of preserving its germplasm, and of providing stock for out-planting to supplement the tiny wild population and to establish new ones in suitable habitat. In particular, consideration should be made of re-establishing a population in the Torrey Pines State Park, as well as other former sites where habitat is still suitable.
U.S. Fish and Wildlife Service
Carlsbad Field Office
2730 Loker Avenue West
Carlsbad, California 92008-6603
Telephone: (760) 431-9440
Fax: (760) 431-9624
U.S. Fish and Wildlife Service. 7 October 1996. "Endangered and Threatened Wildlife and Plants; Determination of Endangered or Threatened Status for Four Southern Maritime Chaparral Plant Taxa from Coastal Southern California and Northwestern Baja California, Mexico." Federal Register 61 (195): 52370-52384.