San Clemente Island Larkspur

Delphinium variegatum ssp. kinkiense

Description

San Clemente Island larkspur, Delphinium variegatum ssp. kinkiense, is a perennial herb, growing 4-20 in (10-50 cm) in height, having a woody branching root. The three-part or "trifid" leaves diminish in size from the bottom to top of the stem. The flowerhead, called an inflorescence, is formed of eight to 10 flowers with off-white petals and dark anthers.

This larkspur germinates between November and February; leafing occurs in February and budding in March; anthesis occurs March through May; fruiting May through July; and seed dispersal June through August by wind and rain.

Habitat

Situated 64 mi (102 km) west-northwest of San Diego, San Clemente Island is almost 21 mi (33 km) long and about 4 mi (6.5 km) wide at its widest point. The highest elevation, Mount Thirst, is near the center of the island at 1,965 ft (599 m). The island supports a diverse fauna dispersed through several ecological zones, determined by elevation and by proximity to the ocean.

San Clemente Island larkspur is usually found in moist grasslands on rich, dark loam. A few plants have been found in shallower, eroded soils, but these do not seem to be thriving. Field observations following wild fires suggest that this species is adapted to fire during its dormant period.

Distribution

This species is endemic to San Clemente Island, the largest of the California Channel Islands.

The larkspur grows at 30 locations on San Clemente Island. The island is under the jurisdiction of the U. S. Navy, which operates a research and development facility there.

Threats

Grazing and trampling by feral goats and rooting by pigs are considered the principal reasons for the decline of this species. The larkspur is threatened by the continuing decrease of grassland and is vulnerable to disturbance caused by road construction or by military maneuvers on the island.

Conservation and Recovery

In compliance with provisions of the Endangered Species Act, the U. S. Navy has consulted with the U. S. Fish and Wildlife Service to develop a management plan to study and preserve rare plants and wildlife on San Clemente Island. Potentially, the larkspur could hybridize with another island Delphinium and lose its genetic integrity. The proximity of the second plant will influence the selection of sites when transplantation of the larkspur is attempted.

The recovery plan recommends revegetating the habitat with plants and seed of native non-sensitive plants and controlling erosion by constructing check dams. Once the habitat has been restored, larkspur cultivated from wild stock should be transplanted.

Contacts

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
http://pacific.fws.gov/

Natural Resources Office
Staff Civil Engineer (18N)
NAS North Island (Bldg 3)
San Diego, California 92135-5018

References

Philbrick, R. N., and J. R. Haller. 1977. "The Southern California Islands." In M. G. Barbour and J. Major, eds., Terrestrial Vegetation of California. John Wiley and Sons, New York.

U. S. Fish and Wildlife Service. 1984. "Recovery Plan for the Endangered and Threatened Species of the California Channel Islands." U. S. Fish and Wildlife Service, Portland, Oregon.