Peritoma serrulata. Synonym: Cleome serrulata. (Rocky Mountain Bee Plant)
Cleomaceae.  Synonym: Capparaceae (Caper Family)  (Cleome Family)

Foothills, montane.  Roadsides, disturbed areas. Summer, fall.
Above: Carpenter Natural Area, August 15, 2017.
Left: Denny Lake, Cortez, September 6, 2007.

Cleome serrulata can grow to six feet tall with very attractive pink flowers having long exserted stamens. 

Leaves (best seen in the right center of the photograph at left) are palmately compound  with three long and narrow divisions.  The plant is found along roadsides and other disturbed areas and often grows in attractive clusters of many plants.

The Cleome family was named by Linnaeus in 1753. This species was placed in that family and named Cleome serrulata by Frederick Pursh in 1814 from a collection made by Meriwether Lewis: "August 25, 1804, growth of the open Prairies" along the Vermillion River of South Dakota.

Augustin de Candolle named the Peritoma genus and moved this species to that genus, keeping the genus in Cleomaceae. 

"Peritoma" is from the Greek "peri" (all around) and "tome" (a slice), alluding to the cut of the calyx base. "Serrulata" means "fine toothed" and refers to the minutely serrated sepals.

Peritoma serrulata. Synonym: Cleome serrulata. (Rocky Mountain Bee Plant)
Cleomaceae.  Synonym: Capparaceae (Caper Family)  (Cleome Family)

Foothills, montane.  Roadsides, disturbed areas. Summer, fall.
Denny Lake, Cortez, September 6, 2007.

Fruits are pendulous and from 1 to 3 inches long.

Click to see the closely related Peritoma lutea.

Peritoma serrulata. Synonym: Cleome serrulata. (Rocky Mountain Bee Plant)
Cleomaceae.  Synonym: Capparaceae (Caper Family)  (Cleome Family)

Foothills, montane.  Roadsides, disturbed areas. Summer, fall.
Denny Lake, Cortez, September 6, 2007.

Peritoma serrulata. Synonym: Cleome serrulata. (Rocky Mountain Bee Plant)
Cleomaceae.  Synonym: Capparaceae (Caper Family)  (Cleome Family)

Foothills, montane.  Roadsides, disturbed areas. Summer, fall.
Denny Lake, Cortez, September 6, 2007.

Leaflets are long, narrow, and in threes, quite reminiscent of Trifolium leaves of Fabaceae (Pea Family).

Range map © John Kartesz,
Floristic Synthesis of North America

State Color KeySpecies 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 Peritoma serrulata