Semi-desert, foothills, montane. Openings, shrublands. Summer.
Near McPhee Reservoir, July 21, 2005.

Tetradymia canescens is a small bush from a few inches tall to three feet. It inhabits dry foothill meadows and stands out especially because of its very gray (Latin: "canescens") leaves and, in blooming time, because of its massing of golden flowers.  Tetradymia canescens is easily mistaken for Rabbitbrush and is a close cousin.

"Tetradymos" means "four-sided", referring to the four phyllaries that subtend the flower head (see the second photograph below).

The first plant of this species was collected for science by David Douglas near the Columbia River in the early 1830s. This was the first member of its genus; Augustin de Candolle named both the genus and this species in 1838.

Semi-desert, foothills, montane. Openings, shrublands. Summer.
Near McPhee Reservoir, July 21, 2005.

Tetradymia canescens presents a very soft and velvety appearance, quite in contrast to its ragged, thorny cousin, Tetradymia spinosa, pictured below.

Semi-desert, foothills, montane. Openings, shrublands. Summer.
Near McPhee Reservoir, July 21, 2005.

The very downy ("canescent"), bulging, four phyllaries can be seen below the tube of yellow disk flowers.

Semi-desert, foothills. Openings, shrublands. Spring.
Canyons of the Ancients National Monument, April 27, 2007.

Although this species of Tetradymia shares a number of characteristics with T. canescens, it is distinguished in two major ways:  it has very prominent hooked spines (visible in the photograph below) and it blooms in the spring, not summer.  T. spinosa is densely white hairy and this lures you to touching it, but the spines quickly put an end to this intimacy.  Flowers are brilliant yellow and numerous.

William Hooker and George Arnott named this species in 1839 from a specimen collected by Tolmie in Idaho.

Semi-desert, foothills. Openings, shrublands. Spring.
Canyons of the Ancients National Monument, April 27, 2007.

The branch at the left side of the photograph is young and its just developing spines are pliable and not too threatening; the branch at top right grew last year, is now woody, and shows the fully developed curved, sharp, blood-letting spines.

Semi-desert, foothills. Openings, shrublands. Spring.
Canyons of the Ancients National Monument, April 27, 2007.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Tetradymia canescens

Range map for Tetradymia spinosa