Santa Ana River Woolly-star

Eriastrum densifolium ssp. sanctorum

Description

Santa Ana River woolly-star, Eriastrum densifolium ssp. sanctorum, is a low shrub reaching a maximum height of about 3.3 ft (1 m). Its branching, woody stems and profuse leaves are gray-green. Large, bright blue flowers cluster in groups of about 20 per flowerhead.

Habitat

Santa Ana woolly-star is an important member of a scrub community that is found on higher elevation flood plain terraces of the Santa Ana River and its tributaries. It occurs in full sunlight in the sandy-silty soils of fan-shaped alluvial deposits. Alluvial fans form where tributary streams emerge from narrow ravines onto the flood plain of a larger river. An occasional scouring flood appears to maintain this plant community, which is characterized by old California juniper, mountain mahogany, and Yerba Santa. Habitat elevation ranges from 500-2,000 ft (152-610 m).

Distribution

This species is native to the Santa Ana River drainage of southern California in Orange, Riverside, and San Bernardino counties.

Although significant numbers of this plant still survive, the population has declined dramatically within the last decade of the twentieth century, and habitat continues to disappear at a steady rate. Where habitat remains, the woolly-star is found in disjunct stands along the Santa Ana River in San Bernardino County. A remnant population occurs along Lytle Creek within the boundaries of the City of San Bernardino. Woolly-star has been eliminated from Orange and Riverside counties.

Threats

Flood plain habitats in Orange County (part of the Los Angeles metropolitan area) have been densely urbanized. Where it passes through the cities of Costa Mesa, Santa Ana, and Orange, the Santa Ana River has been channeled, and its banks are lined with buildings, parks, and other developments. Beyond the suburb of Orange, the river is paralleled by a major expressway that runs into Riverside County. Here, citrus groves and other agricultural developments abut the river. Higher flood plain terraces have been developed into residential neighborhoods, livestock ranches, or citrus groves. In San Bernardino County, the Santa Ana River has been channeled for part of its course, and land is developed to the water's edge.

Surviving populations of the plant are currently threatened by active and proposed sand and gravel mining on Bureau of Land Management (BLM) lands. The BLM has prepared a management plan to conserve this species, while allowing limited mining to continue. Parcels of BLM land in this area, however, are in the process of being transferred to state and county jurisdiction, which would remove them from the protection of the Endangered Species Act. San Bernardino County has required some sand and gravel operators to avoid populations of this species and to transplant others, but this has had little effect in preventing overall habitat loss.

The U. S. Army Corps of Engineers has proposed new flood control dams for the Upper Santa Ana River Canyon and Lytle Creek. If these dams are built, zoning restrictions that now apply to flood plain development downstream would probably be relaxed, encouraging further development and habitat loss. The Corps is required by law to consider the effect of proposed flood control projects on federally listed species.

Conservation and Recovery

The California Fish and Game Commission has listed Santa Ana River woolly-star as Endangered, which provides some protection from collecting, but not from habitat destruction. Because this shrub has been successfully transplanted to other sites in the past, the U. S. Fish and Wildlife Service Recovery Plan for the woolly-star will recommend transplanting shrubs to protected sites within the historic range.

Contact

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/

References

Krantz, T. 1984. "A Review of the Endangered Status of the Slender-Horned Spineflower Centrostegia leptoceras Gray and the Santa Ana River Woolly-star Eriastrum densifolium ssp. sanctorum Mason." Report. Bio-Tech Planning Consultants, Bear Lake, California.

U. S. Fish and Wildlife Service. 1987. "Determination of Endangered Status for Santa Ana River Woolly-star, Eriastrum densifolium ssp. sanctorum." Federal Register 52(187): 36265-38270.

Zembal, R., and K. J. Kramer. 1984. "The Known Limited Distribution and Unknown Future of Santa Ana River Eriastrum." Crossosoma 10(5): 1-8.