Idaho OnePlan recommends the website of the Idaho Weed Awareness Campaign as the best resource for up-to-date information about Idaho's noxious weeds, and their control.
Source for this page: Idaho's Noxious Weeds by Robert H. Callihan & Timothy W. Miller

BACKGROUND

Perennial pepperweed (Lepidium latifolium) is native to southern Europe and western Asia. It spreads by seed and creeping roots under many different environmental conditions.

(Thumbnail images are linked to a larger photo)

DESCRIPTION

Perennial pepperweed grows up to 6 feet tall and has basalAt the base of plant or plant part leaves that are lance shaped, have long petiolesleaf stalks, are up to 12 inches long, and are covered with a waxy layer. Stem leaves are smaller and have shorter petioles, but don't claspLeaves that appear to wrap around the stem at their base the stem. Leaves have a prominent, whitish midveinThe center and usually most prominent vein on a leaf. Flowers are white, less than 1/8 inch wide, and are borne in dense, rounded clusters at the branch tips from early summer until fall. Fruits are roundish, slightly hairy, measure 1/16 inch in diameter, and contain 2 tiny seeds.

DISTRIBUTION

Perennial pepperweed is widely scattered throughout the U.S. and in many Idaho counties.

CONTROL

No biological control agents are available for perennial pepperweed, but herbicides are available to provide control.