Cleome platycarpa is a relatively small annual herb, usually less than two feet tall. The stem can be simple or branched and is hairy and purplish green. The seed pods are oblong and lightly hairy. The flowers are bright yellow with four petals and many long stamens, blooming between March and July (Armstrong and Thornber, 1915; Hickman, 1993; Rickett, 1973). Flowers are lightly sweet smelling while the rest of the plant has a somewhat unpleasant odor (Wilder, 1932).

Cleome platycarpa is found in the North American Great Basin Desert shrub-steppe community, which is within a cold desert biome (Woodward, 2003). It is native to eastern Oregon, southwestern Idaho, northern Nevada, to northeastern California, USA (USDA, 2012). It grows in alkaline, clay, or volcanic tuff soils and often in sagebrush scrub (Hickman, 1993). The base and crevices of the otherwise barren clay hills at the Painted Hills Unit of the John Day Fossil Beds in eastern Oregon are carpeted in the yellow blooms of Cleome platycarpa in the early summer.

Cleome platycarpa is native to an area west of the Rocky Mountains and east of the Cascades in the USA. It can be found in eastern Oregon, southwestern Idaho, northern Nevada, to northeastern California (Rickett, 1973; USDA, 2012).

Peritoma platycarpa (Torr.) H.H. Iltis:
United States (North America)

Cleome platycarpa Torr.:
United States (North America)

United States

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Cleome platycarpa can be found in alkaline, clay, or volcanic tuff soils, often in sagebrush scrub; 800-1500 m (eFloras, 2008; Hickman, 1993). The base and crevices of the otherwise barren clay hills at the Painted Hills Unit of the John Day Fossil Beds in eastern Oregon are carpeted in the yellow blooms of Cleome platycarpa in the early summer.

In the 2010 study of the origins of C4 photosynthesis in Cleomaceae, Feodorova et al. used Internal Transcribed Spacer (ITS) analysis to reconstruct the family’s phylogenetic tree. The trees published in this study indicate that Cleome serrulata is the closest relative to Cleome platycarpa (Feodorova et al., 2010). Cleome serrulata distribution is more widespread than Cleome platycarpa (USDA, 2012). Some botanists believe Cleome platycarpa and five other species belonging to the genus Cleome should be separated into a new genus, Peritoma (Iltis and Cochrane, 2007). The most recent published research in the phylogeny of Cleome suggests more research is needed before making this reclassification (Feodorova et al., 2010).

Rounded Global Status Rank: G5 - Secure

United States

Rounded National Status Rank: NNR - Unranked

The Sahaptin-speaking Native Americans who once inhabited a large portion of southeastern Washington and northeastern Oregon used Cleome platycarpa medicinally. They would drink an infusion of the mashed plant or rub the plant on the body to treat children’s colds and fever. There are no known current uses for this plant (Hunn, 1990).