perennial pepperweed
(Lepidium latifolium L.)

Overview

Appearance

Lepidium latifolium is a perennial that can grow from 1-5 ft. (0.3-1.5 m) in height. In the late fall to early spring a rosette of leaves develops with 4-12 in. (10-30 cm) long and 1-2 in. (2.5-5 cm) wide, toothed leaves. Plants emerge from thick, minimally branched roots or semi-woody crowns. Individuals remain as a rosette for several weeks before the stem elongates.

Foliage

Rosette leaves are long petiolate. Cauline (stem) leaves are alternate, 1-3 in. (2.5-7.6 cm) long and oblong.

Flowers

Flowering occurs in the late spring to summer, when flat, dense clusters of flowers develop at the apex of the flowering stem. Individual flowers are 4-petaled and white.

Fruit

The fruit is a round to oval, hairy capsule that is 0.06 in. (1.5 mm) in diameter. It contains a single seed.

Ecological Threat

Lepidium latifolium invades coastal wetlands, riverbanks, marshes, rangelands, and roadsides. It can form dense monocultures that can increase in size over time crowding out native species. This plant was accidentally introduced into the United States around 1936 as contaminant in seed. It is native to Eurasia.

Resources

• Element Stewardship Abstract - The Nature Conservancy
• Weed of the Week - USDA Forest Service

Selected Images

Maps

Invasive Listing Sources

• Alaska Noxious Weeds
• Alberta Weed Control Act
• California Invasive Plant Council
• California Noxious Weeds
• Colorado Noxious Weeds
• Connecticut Invasive Plant List
• Connecticut Invasive Plant Working Group
• Connecticut Noxious Weeds
• Hawaii Noxious Weeds
• Idaho Noxious Weeds
• Indiana Invasive Species Council - Invasive Plant List
• Indiana Terrestrial Plant Rule
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
• Massachusetts Invasive Plants Advisory Group List
• Massachusetts Noxious Weeds
• Massachusetts Prohibited Plant List
• Montana Noxious Weeds
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Nevada Noxious Weeds
• New Hampshire Prohibited Invasive Species
• New Invaders of the Northeast and Northcentral
• New Invaders of the Southeast
• New Mexico Noxious Weeds
• New York Regulated and Prohibited Invasive Species - Prohibited
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• Rhode Island Natural History Survey
• Utah Noxious Weeds - Contain
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States
• Wisconsin Noxious Weeds
• Wisconsin's Invasive species rule – NR 40
• Wyoming Noxious Weeds

References