Regularity: Regularly occurring
Regularity: Regularly occurring
Global Range: The range in CA is only about 40 sq mi, since this plant just barely gets into the United States. However, it ranges quite far south in Baja.
Catalog Number: US 313846
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Original publication and alleged type specimen examined
Preparation: Pressed specimen
Collector(s): A. W. Anthony
Year Collected: 1897
Locality: Cedros Island, Baja California Norte, Mexico, North America
- Holotype: Rydberg, P. A. 1922. N. Amer. Fl. 33: 36.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 21 - 300
Comments: 10 extant in California as of 2005. Unknown number of occurrences in Baja, Mexico. Distribution in Baja extends pretty far south so there are likey large numbers of occurrences there.
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
Rounded National Status Rank: N2 - Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G3 - Vulnerable
Reasons: Ambrosia chenopodiifolia is known from southern California, where there are only about 10 sites, south into Baja, Mexico where there are probably numerous sites. The number of plants is only known for California where there are 1400 (as of 2005), but there are likely to be many thousands south of the border. The threats are fairly severe in CA; Baja threats are unknown.
Environmental Specificity: Broad. Generalist or community with all key requirements common.
Comments: Pretty broad, occurring in coastal scrub from southern CA south far into Baja, Mexico.
Global Short Term Trend: Unknown
Global Long Term Trend: Unknown
Degree of Threat: High
Comments: Threats recorded for CA occurrences include border patrol activities, trampling, vehicle trampling, development, gravel mining, dumping, and invasive plants. In Baja, threats may be slightly less since the plant ranges over a wider area, but locally probably includes development and other threats.
Ambrosia chenopodiifolia is a species of ragweed known by the common names San Diego bursage and San Diego bur ragweed. It is native to Baja California, and southern California as far north as San Diego County, where it is a member of the coastal sage scrub plant community.
Ambrosia chenopodiifolia is a thickly branching shrub exceeding 3 meters in maximum height. The leaves are ovals up to 3 centimeters long and coated in white hairs. They are sometimes lobed.
Like other ragweeds it is monoecious, with each inflorescence bearing heads of pistillate (female) flowers below a cluster of staminate (male) flowers. The inflorescence is spiny, especially when in fruit. The fruit is a spherical, woolly bur about half a centimeter long covered in hooked spines.
- Ambrosia chenopodiifolia. NatureServe. 2012.
- Jepson Manual Treatment — Ambrosia chenopodiifolia
- USDA Plants Profile
- Ambrosia chenopodiifolia Photo gallery
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