Ambrosia chamissonis (Less.) Greene
silver burweed (silver burr ragweed)
Asteraceae (Aster family)

Introduction to Vascular Plants


© Dawn Hanna     (Photo ID #10550)


E-Flora BC Static Map

Distribution of Ambrosia chamissonis
Click here to view the full interactive map and legend

Species Information

Perennial herb from long, creeping rhizomes; stems leafy, spreading-hairy, stout, branched just below the surface, forming large, lax clumps 20-160 cm tall.
Succulent, mostly alternate, oblong to rounded in outline, about 4-14 cm long with stalks 2-7 cm long, the blades pinnately dissected or rarely simple and toothed, finely whitish- or silvery-haired.
Male (sterile) heads nearly unstalked or short-stalked, 4-6 mm wide, in congested, leafless, terminal spikes about 8 cm long; female (fruiting) heads egg-shaped, 1-flowered;fruiting involucres 1-beaked, 6-11 mm long, glandular and finely hairy burs with 2-4 series of spines or prickles.
Achenes enclosed within the involucral bracts; pappus lacking.

SourceThe Illustrated Flora of British Columbia


If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.


Ecological Framework for Ambrosia chamissonis

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres)
193 0 1020
Slope Gradient (%)
1 0 5

Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]

92 50 135
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
2 1 6
Modal Nutrient Regime
# of field plots
 species was recorded in:
Modal BEC Zone Class

All BEC Zones (# of stations/zone) species was recorded in

BWBS(1), CWH(9), MS(2)

Habitat and Range

Moist to mesic coastal sandy or gravelly upper beaches and shorelines in the lowland zone; common in coastal BC; S to CA.

SourceThe Illustrated Flora of British Columbia


Synonyms and Alternate Names:
Ambrosia chamissonis var. bipinnatisecta (Less.) J.T. Howell
Franseria chamissonis Less.
Franseria chamissonis subsp. bipinnatisecta (Less.) Wiggins & Stockw.
Franseria chamissonis var. bipinnatisecta Less.