Linnaeus named this genus in 1753.  The species was named  by famed collector and Harvard Professor, Thomas Nuttall in Torrey and Gray's 1838 Flora of North America.  Nuttall was also the first to collect this plant, probably in 1835, on his trip west with the Wyeth Expedition of 1834-1837.

Semi-desert, foothills, montane. Disturbed areas, openings. Spring, summer.
Butler Wash near the San Juan River, Utah, April 8, 2005.  Canyonlands National Park, Utah, April 12, 2005.

Western Peppergrass is abundant in Pinyon/Juniper forests and is also common in the mountains.  One very common spring blooming variety (pictured at left and directly below) has many stems, making it almost appear to be a small shrub.  Lower leaves are lobed or broadly pinnatified (in this case, with few lobes, similar to a fleur-de-lis); upper leaves are usually linear.

An abundance of tiny, fragrant, white flowers is the main attraction of this very showy and common plant.   

Semi-desert, foothills, montane. Disturbed areas, openings. Spring, summer.
Canyons of the Ancients National Monument, April 1, 2005.

Lepidium montanum is a highly variable species with about eight varieties in Colorado.  The spring blooming variety at left has far fewer stems and a much more open growth pattern than the one pictured above.  Its basal leaves have many lobes. 

Semi-desert, foothills, montane. Disturbed areas, openings. Spring, summer.
Canyons of the Ancients National Monument, August 22, 2005.

This tall, late summer blooming variety of Lepidium montanum is very common and long-lasting in Pinyon/Juniper forest openings and along roads.  Flowers and seeds are very similar to the other L. montanums shown on this page.  Basal leaves are usually withered at blooming time.  Stems may be single or multiple from the base and may branch at about a forty-five degree angle from anywhere on the stem but there are usually few branchings.  As a result the plant has a very open and airy appearance and it is top-heavy with flowers and seeds.