Ambrosia monogyra
Singlewhorl burrobrush, singlewhorl burrobrush, singlewhorl burrobrush
(c) Rose Zappa, some rights reserved (CC BY) · licence
Family: Asteraceae · Type: Shrub · Native
Conservation status: CNPS 2B.2
Ambrosia monogyra (Singlewhorl burrobrush) is a native California shrub in the Asteraceae family, recognized by single whorl of wings diagnostic vs spiraled wings of relatives.
Singlewhorl burrobrush is a rare (CNPS 2B.2) California native shrub found in southwestern California, eastern Sierra Nevada, and desert southern regions in washes and dry riverbeds at elevations below 500 meters. Flowering from September to November, this plant produces small, inconspicuous heads of staminate and pistillate flowers in tight clusters. Growing as a much-branched shrub 1 to 4 meters tall with glabrous, resinous stems, it forms an open, leafy panicle-like structure. Its distinctive leaves are 2 to 5 centimeters long, thread-like or with few thread-like lobes, with grooved upper surfaces and glabrous, resinous undersides. The fruit is a distinctive bur 2 to 5 millimeters long with 7 to 12 wings arranged in a single central whorl.
Identification and appearance
Key characters: 15 sympatric species; single whorl of wings diagnostic vs spiraled wings of relatives
Habitat and range
Habitat: Washes, dry riverbeds
Elevation: < 500 m
California counties: San Diego, San Bernardino, Imperial, Inyo
Outside California: to western Nevada, Texas, northern Mexico
Bloom period
Ambrosia monogyra blooms Sep-Nov.
Conservation status
CNPS 2B.2
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 monogyra native to California?
Yes. Ambrosia monogyra is native to California (recorded as native).
When does Ambrosia monogyra bloom?
Ambrosia monogyra blooms Sep-Nov.
Where in California does Ambrosia monogyra grow?
Ambrosia monogyra occurs in San Diego, San Bernardino, Imperial, Inyo, at elevations of < 500 m.
What plant family does Ambrosia monogyra belong to?
Ambrosia monogyra is in the Asteraceae family, genus Ambrosia.
Is Ambrosia monogyra rare or endangered?
Ambrosia monogyra carries California Rare Plant Rank 2B.2, state rank S2.
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.