Ambrosia pumila
San diego ambrosia, San Diego Ambrosia, San Diego ambrosia, San Diego ambrosia
Photo by Chez Brungraber
Family: Asteraceae · Type: Herb · Native
Conservation status: CNPS 1B.1 · Endangered
Ambrosia pumila (San diego ambrosia) is a native California herb in the Asteraceae family, recognized by small stature and finely divided silvery leaves.
San diego ambrosia is a rare (CNPS 1B.1) California native perennial found in southern coastal California and the Peninsular Ranges in Riverside and San Diego counties, growing in disturbed sites at elevations of 50 to 600 meters. Flowering from April to July, this plant produces pale flower heads in small clusters 3 to 5 millimeters in diameter. Growing 10 to 35 centimeters tall with colonial roots and erect, few-branched stems densely covered in short hairs, it spreads through rhizome-like underground roots. Its leaves are 3 to 13 centimeters long, lanceolate to widely ovate, with complex pinnately divided lobes that are densely covered in grayish-white hairs. The plant produces small bur-like fruits 2 to 2.5 millimeters long, occasionally bearing 1 to 5 vestigial spines.
Identification and appearance
Key characters: 11 sympatric species; small stature and finely divided silvery leaves
Habitat and range
Habitat: Disturbed sites
Elevation: 50-600 m
Outside California: Baja California
Bloom period
Ambrosia pumila blooms Apr-Jul.
Conservation status
CNPS 1B.1 · Endangered
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 pumila native to California?
Yes. Ambrosia pumila is native to California (recorded as native).
When does Ambrosia pumila bloom?
Ambrosia pumila blooms Apr-Jul.
What plant family does Ambrosia pumila belong to?
Ambrosia pumila is in the Asteraceae family, genus Ambrosia.
Is Ambrosia pumila rare or endangered?
Ambrosia pumila carries California Rare Plant Rank 1B.1, state rank S1.
What habitat does Ambrosia pumila grow in?
Ambrosia pumila grows in Disturbed sites.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
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.