Tetradymia canescens
Gray horsebrush
(c) Tim Messick, some rights reserved (CC BY), uploaded by Tim Messick · licence
Family: Asteraceae · Type: Shrub · Native
Tetradymia canescens (Gray horsebrush) is a native California shrub in the Asteraceae family, recognized by unique as completely unarmed species with flat-topped inflorescence.
Gray horsebrush is a California native shrub found in the Sierra Nevada, Transverse Ranges, southern Peninsular Ranges, Great Basin, and Mojave Desert in sagebrush scrub, pinyon and juniper woodland, and conifer forest at elevations of 1,000 to 3,400 meters. Flowering from July to October, this plant produces creamy to bright yellow flowers in clusters of 3 to 6 heads, with each flower head 6 to 8 millimeters long. Growing 1 to 8 decimeters tall with unevenly tomentose stems that become nearly smooth in stripes below the nodes, it forms a distinctive silvery-green shrub. Its leaves are oblanceolate, less than 4 centimeters long, covered in a dense tomentose or silvery indumentum, with smaller clustered leaves surrounding the main branches. The fruit is 2.5 to 5 millimeters long, topped with fine white bristles 6 to 11 millimeters in length.
Identification and appearance
Key characters: 8 sympatric species; unique as completely unarmed species with flat-topped inflorescence
Habitat and range
Habitat: Sagebrush scrub, pinyon/juniper woodland, conifer forest
Elevation: (700)1000-3400 m
Outside California: to British Columbia, Montana, Wyoming, New Mexico
Bloom period
Tetradymia canescens blooms Jul-Oct.
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 canescens native to California?
Yes. Tetradymia canescens is native to California (recorded as native).
When does Tetradymia canescens bloom?
Tetradymia canescens blooms Jul-Oct.
What plant family does Tetradymia canescens belong to?
Tetradymia canescens is in the Asteraceae family, genus Tetradymia.
What habitat does Tetradymia canescens grow in?
Tetradymia canescens grows in Sagebrush scrub, pinyon/juniper woodland, conifer forest.
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.