Ambrosia chamissonis
Beach bur-sage, Beach Bur-Sage
(c) Eric in SF, some rights reserved (CC BY-SA) · licence
Family: Asteraceae · Type: Shrub · Native
Ambrosia chamissonis (Beach bur-sage) is a native California shrub in the Asteraceae family, recognized by unique coastal habitat and mat-forming habit.
Beach bur-sage is a California native perennial found in coastal bioregions including northern, central, and southern California Coast and Channel Islands on beaches and dunes at elevations below 25 meters. Flowering from May to October, this plant produces small clustered heads of yellowish flowers with staminate and pistillate flowers on the same plant. Growing as a mat-forming plant with decumbent or prostrate stems less than 4 meters long, it spreads across sandy landscapes with densely hairy, grayish-green foliage. Its leaves are oblanceolate to elliptic, 2 to 5 centimeters long, with deeply toothed or lobed edges that create a distinctive textured appearance. The fruit is a distinctive bur 5 to 10 millimeters long, covered in 10 to 20 spiraled spines that aid in seed dispersal by catching onto passing animals or clothing.
Identification and appearance
Key characters: 11 sympatric species; unique coastal habitat and mat-forming habit
Habitat and range
Habitat: Beaches, dunes
Elevation: < 25 m
Outside California: to British Columbia, Baja California, also western South America
Bloom period
Ambrosia chamissonis blooms May-Oct.
How to tell it apart
vs Artemisia: Ambrosia produces spiny burs as fruits; Artemisia has tiny dry fruits without spines and strongly aromatic foliage.; vs Atriplex: Ambrosia has flower heads in spikes producing spiny burs; Atriplex has inconspicuous flowers with papery bracts and scurfy gray foliage.; vs Baccharis: Ambrosia has both male and female flowers on the same plant; Baccharis has male and female flowers on separate plants.; vs Eriogonum: Ambrosia has greenish flower heads producing spiny burs; Eriogonum has showy clusters of white, pink, or yellow flowers with papery bracts.; vs Salvia: Ambrosia has inconspicuous greenish flowers in the Asteraceae; Salvia has showy tubular lipped flowers typical of mints.
Frequently asked questions
Is Ambrosia chamissonis native to California?
Yes. Ambrosia chamissonis is native to California (recorded as native).
When does Ambrosia chamissonis bloom?
Ambrosia chamissonis blooms May-Oct.
What plant family does Ambrosia chamissonis belong to?
Ambrosia chamissonis is in the Asteraceae family, genus Ambrosia.
What habitat does Ambrosia chamissonis grow in?
Ambrosia chamissonis grows in Beaches, dunes.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.