E-Flora BC: Electronic Atlas of the Flora of British Columbia

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

Introduction to Vascular Plants

Distribution of Ambrosia chamissonis
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Species Information

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Illustration Source: The Illustrated Flora of British Columbia

General:
Perennial herb from long, creeping rhizomes; stems leafy, spreading-hairy, stout, branched just below the surface, forming large, lax clumps 20-160 cm tall.

Leaves:
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.

Flowers:
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.

Fruits:
Achenes enclosed within the involucral bracts; pappus lacking.

Source: The Illustrated Flora of British Columbia

Key to the Species and Taxonomic Notes

1. Involucres with 2-4 series of short, sharp spines; leaves mostly alternate................A. chamissonis

1. Involucres with a single series of short spines or tubercles above the middle; leaves, or at least the lower ones, opposite.

2. Plants annual from fibrous roots; leaves mostly stalked, mostly twice pinnatifid; involucres with short spines..................A. artemisiiifolia

2. Plants perennial from creeping roots; leaves short-stalked or nearly unstalked, only once-pinnatifid; involucres with tubercles......................A. psilostachys

Source: Illustrated Flora of British Columbia

Habitat / Range

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

Source: The Illustrated Flora of British Columbia

Ecology

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
Site Information	Minimum	Average	Maximum
Elevation (metres)	0	193	1020
Slope Gradient (%)	0	1	5
Aspect (degrees) [0 - N; 90 - E; 180 - S; 270 - W]	50	92	135
Soil Moisture Regime (SMR) [0 - very xeric; 4 - mesic; 8 - hydric]	1	2	6
Modal Nutrient Regime Class	A
Number of field plots species was recorded in:	12
Modal BEC Zone Class	CWH
All BEC Zones (# of stations/zone) species was recorded in:	BWBS(1), CWH(9), MS(2)
Source: Klinkenberg 2020

Climate

The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Status Information

Origin Status	Provincial Status	BC List (Red Blue List)	COSEWIC
Native	S5	Yellow	Not Listed

BC Ministry of Environment: BC Species and Ecosystems Explorer, the authoritative source for conservation information in 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.

Taxonomic and Nomenclatural Links

Flora North America treatment for Asteraceae
Flora North America treatment for Ambrosia chamissonis
Genetic information (NCBI Taxonomy Database)
International Plant Names Index
Taxonomic Information from the World Flora Online
Integrated Taxonomic Information System

Additional Range and Status Information Links

Burke Museum of Natural History (Washington State records)
CalFlora
Consortium of Pacific Northwest Herbaria records
Jepson Interchange
NatureServe Explorer
USDA

Additional Photo Sources

Images From CalPhoto
UT Austin's Native Plant Database
Google Image Search
Flickr Image Search

General References

Google Scholar Search
Family References
General Botanical References for BC

Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2020. E-Flora BC: Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2024-05-11 11:18:51 PM ]

Disclaimer: The information contained in the E-Flora atlas pages is derived from expert sources as cited in each section. This information is scientifically based. E-Flora also acts as a portal to other sites via deep links. As always, users should refer to the original sources for complete information. E-Flora BC is not responsible for the accuracy or completeness of the original information.