Tetradymia sp.
Cottonthorn, horsebrush, Horsebrush
(c) Tim Messick, some rights reserved (CC BY), uploaded by Tim Messick · licence
Family: Asteraceae · Type: Shrub · Native
Tetradymia sp. (Cottonthorn) is a native California shrub in the Asteraceae family.
How to tell it apart
vs Ericameria: Tetradymia has 4-6 bracts in 1-2 rows; Ericameria has many bracts in 5 vertical rows.; vs Artemisia: Tetradymia has rigid spine-tipped branches; Artemisia has soft, non-spiny aromatic foliage.; vs Lycium: Tetradymia has yellow composite flowers; Lycium has tubular purple/greenish flowers with 5 petals.; vs Senecio: Tetradymia has 4-8 flowers per head with woolly appearance; Senecio has more flowers per head and often ray petals.; vs Krascheninnikovia: Tetradymia has yellow composite flowers; Krascheninnikovia has tiny greenish flowers without petals (Chenopodiaceae family).
Frequently asked questions
Is Tetradymia sp. native to California?
Yes. Tetradymia sp. is native to California (recorded as native).
What plant family does Tetradymia sp. belong to?
Tetradymia sp. is in the Asteraceae family, genus Tetradymia.
Related species
Other California species in the same genus, family, or bioregion.
- Tetradymia spinosa — Shortspine horsebrush
- Tetradymia stenolepis — Mojave cottonthorn
- Tetradymia tetrameres — Dune horsebrush
- Tetradymia argyraea — Striped horsebrush
- Tetradymia axillaris — Catclaw horsebrush
- Tetradymia axillaris var. axillaris — Catclaw horsebrush
- Tetraneuris acaulis var. arizonica — Arizona four nerve daisy
Sources: Jepson eFlora · CalPhotos
Last updated 2026-04-14
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.