San Diego Bur-Sage [Ambrosia chenopodiifolia (Benth.) Payne]

San Diego Bur-Sage [Ambrosia chenopodiifolia (Benth.) Payne]

Listing CNPS List 2 R-E-D Code 2-2-1

State/Federal. Status -- None ASTERACEAE Apr.-Jun.

Global Rank G5 State Rank S1.1

Distribution: Southern San Diego County; Baja California, Mexico

Habitat: An arid phase of Diegan Sage Scrub is the preferred U.S. habitat of this shrub. Typically, San Diego Bur-Sage grows with Artemisia californica and Salvia mellifera in a low-growing, fairly open sage scrub. Olivenhain cobbly loam is the soil mapped for the San Ysidro population.

Known Sites: Sizeable populations occur on the hillsides of northern Spring Canyon in Otay Mesa. A small population of the San Diego Bur-sage was recently extirpated near Greg Rogers Park by a housing development and brushfire. The northernmost population occurs in Rice Canyon where the two shrubs noted will likely be extirpated by a major development. The site of an old report from near Brandywine Avenue in Chula Vista may have been developed for housing. Thousands of shrubs grow east of Beyer Boulevard and south of San Ysidro Junior High School where it is the dominant plant. A hillside dominated by San Diego Bur-Sage grows east of Otay Mesa Place. An old biological report notes a population in Moody Canyon on Otay Mesa. Data Base reports are from east of Dennery Canyon on Otay Mesa, north of Otay Valley Road and west of the quarry where the road jogs to the southeast, in Johnson Canyon on Otay Mesa.

Forty-nine specimens from Baja are deposited in the San Diego Herbarium for this regionally common shrub, ranging south to 28 17' North latitude where collected by Moran (SD 64959) near the peninsular divide at the Barril Road. Old reports range even farther south to below 25 North.

Status: San Diego Bur-Sage is declining in the United States with the development of western Otay Mesa. The northern range of this shrub barely enters the U.S., and all substantial stands should be protected.

Copyright May 1994 Craig H. Reiser.

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