Conserving the Nature of America
Press Release
U.S. Fish and Wildlife Service Proposes Critical Habitat for San Diego Ambrosia

August 26, 2009


Division of Public Affairs
External Affairs
Telephone: 703-358-2220

The U.S. Fish and Wildlife Service (Service) announced today it is proposing to designate 802 acres of land in Riverside and San Diego Counties, California, as critical habitat for Ambrosia pumila (San Diego ambrosia). Areas proposed as critical habitat are identified in 7 units – 3 in Riverside County and 4 in San Diego County.

Area proposed as critical habitat contain sandy loam or clay soils that occur near a river, creek, or other drainage, or within the watershed of a vernal pool, or on an upper terrace; and are in grassland or ruderal habitat types, or openings within coastal sage scrub, that provide adequate sunlight, and airflow for wind pollination. All areas proposed as critical habitat support occurrences of San Diego ambrosia.

San Diego ambrosia has a branching root structure that spreads horizontally underground sprouting new stems each year. These stems generally grow 2 to 12 inches high and may produce yellowish to greenish-colored flowers that appear from May to October. The method by which the plant is pollinated is not well understood, but it is thought to rely on wind. The plant produces very few seeds, diminishing its ability to spread and colonize unoccupied areas.

Many aspects of San Diego ambrosia’s life history remain unknown. We are specifically requesting scientific information to help us more precisely define the physical and biological features essential to the conservation of the plant.

Approximately 263 acres of land in Riverside County are being proposed for exclusion from the final designation because the lands are covered by the Western Riverside County Multiple Species Habitat Conservation Plan. About 278 acres that are covered by either the City of San Diego’s Subarea Plan or the County of San Diego’s Subarea Plan under the Multiple Species Conservation Program are also being proposed for exclusion from the final designation.

Public comments and information about this proposal will be accepted until October 26, 2009. Written requests for a public hearing will be accepted until October 12, 2009. You may submit comments by one of the following methods:
  •, at, or by contacting the Carlsbad Fish and Wildlife Office at 760-431-9440. A draft economic analysis of the proposed rule will be made available for public review and comment at a later date.

Information contained in older news items may be outdated. These materials are made available as historical archival information only. Individual contacts have been replaced with general External Affairs office information. No other updates have been made to the information and we do not guarantee current accuracy or completeness.

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals, and commitment to public service. For more information on our work and the people who make it happen, visit

For more information on our work and the people who make it happen, visit Connect with our Facebook page, follow our tweets, watch our YouTube Channel and download photos from our Flickr page.