Tetradymia tetrameres
Dune horsebrush, Dune Horsebrush
(c) Jim Morefield, some rights reserved (CC BY) · licence
Family: Asteraceae · Type: Shrub · Native
Conservation status: CNPS 2B.2
Tetradymia tetrameres (Dune horsebrush) is a native California shrub in the Asteraceae family, recognized by habitat specialization and very short peduncles.
Dune horsebrush is a rare (CNPS 2B.2) California native shrub found in northern Southeastern Sierra Nevada desert regions in dunes and sagebrush scrub at elevations of 1,200 to 2,100 meters. Flowering from May to September, this plant produces pale yellow flowers in clusters of 4 to 6 heads approximately 8 to 9 millimeters long. Growing to 2 meters tall with tomentose (densely woolly) stems, it develops a distinctive branching structure with soft, thread-like leaves. Its leaves are sparsely tomentose, with main leaves 1 to 4 centimeters long and thread-like, and clustered leaves 10 to 20 millimeters long ranging from thread-like to linear-oblanceolate in shape. The fruit is 5 to 6 millimeters long, densely covered in long soft hairs and topped with approximately 20 stiff bristles.
Identification and appearance
Key characters: 6 sympatric species; diagnostic habitat specialization and very short peduncles
Habitat and range
Habitat: Dunes, deep sand, sagebrush scrub
Elevation: 1200-2100 m
Outside California: western Nevada
Bloom period
Tetradymia tetrameres blooms May-Sep.
Conservation status
CNPS 2B.2
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 tetrameres native to California?
Yes. Tetradymia tetrameres is native to California (recorded as native).
When does Tetradymia tetrameres bloom?
Tetradymia tetrameres blooms May-Sep.
What plant family does Tetradymia tetrameres belong to?
Tetradymia tetrameres is in the Asteraceae family, genus Tetradymia.
Is Tetradymia tetrameres rare or endangered?
Tetradymia tetrameres carries California Rare Plant Rank 2B.2, state rank S2.
What habitat does Tetradymia tetrameres grow in?
Tetradymia tetrameres grows in Dunes, deep sand, sagebrush scrub.
Related species
Other California species in the same genus, family, or bioregion.
- Tetradymia argyraea — Striped horsebrush
- Tetradymia axillaris — Catclaw horsebrush
- Tetradymia axillaris var. axillaris — Catclaw horsebrush
- Tetradymia axillaris var. longispina — Catclaw horsebrush
- Tetradymia canescens — Gray horsebrush
- Tetradymia comosa — Cotton thorn
- Tetraneuris acaulis var. arizonica — Arizona four nerve daisy
- Tetraneuris sp.
- Thelesperma megapotamicum — Rayless greenthread
- Thelesperma sp. — Greenthread
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.