San Clemente Island Broom

Lotus dendroideus var. traskiae

Description

San Clemente Island broom, Lotus dendroideus var. traskiae, is a partially woody, low-growing shrub, 8-48 in (20-120 cm) tall, with slender, erect green branches. Leaves are compound with three leaflets, each 0.2-0.4 in (5-9 mm) long. Flowers are arranged in one-to five-flowered umbels with yellow pistils, which turn orange, then red, with age.

Habitat

Situated 64 mi (102 km) west-northwest of San Diego, San Clemente Island is 21 mi (33 km) long and 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).

San Clemente Island displays a range of habitat types, mostly depending on elevation and proximity to the ocean. Several phases of maritime desert scrub, maritime sage scrub, grasslands, and coastal salt marsh are represented. San Clemente Island broom appears to survive at a variety of elevations and exposures, suggesting a broad habitat tolerance.

Distribution

The plant is locally endemic to San Clemente Island, California. It is closely related to several mainland species, particularly the common deerweed (L. scoparius ).

Six populations of this broom variety are now known on the island of San Clemente. The largest number of plants grow in the vicinity of Wilson Cove. The island falls under the jurisdiction of the U. S. Navy.

Threats

Feral goats nearly denuded San Clemente Island of vegetation at the beginning of the twentieth century and were the primary cause for the decline of broom and other endemics. In the past, construction of military facilities eliminated some plants, but these activities were stopped in 1972. Since the removal of feral goats from most of its habitat, this broom is recovering.

San Clemente Island broom may benefit from light fires but cannot tolerate prescribed burning or heavy wildfires. Fire is a potential threat to the species because of ordinance explosions and prescribed burning by fire station crews.

Public works activities on buildings, roads, and pipelines at Wilson Cove also destroyed some populations.

Conservation and Recovery

The U. S. Navy, in collaboration with the U. S. Fish and Wildlife Service, has developed a management plan to protect and recover rare plants found on the island. The full recovery of the broom may require the use of cultivated plants from the San Clemente Island Native Plant Nursery to supplement natural reproduction. Reintroduction sites must be carefully chosen to exclude other varieties of Lotus to avoid possible hybridization. Further habitat rehabilitation techniques under consideration include erosion control, mechanical mulching, or irrigation.

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
(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

Isley, D. 1978. "New Varieties and Combinations in Lotus, Baptisia, Thermopsis and Sophora (Leguminosae)." Brittonia 30:477-472.

Philbrick, R. N. 1980. "Distribution of Endemic Plants of the California Islands." In D. M. Power, ed., The California Islands: Proceedings of a Multi-Disciplinary Symposium. Santa Barbara Museum of Natural History, Santa Barbara.

Thorne, R. F. 1969. "A Supplement to the Floras of Santa Catalina and San Clemente Islands, Los Angeles County, California." Aliso 7:73-83.

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.