Perennial Pepperweed
Lepidium latifolium

History and Impact

This Class B weed has a limited distribution, and control is required in King County. Perennial pepperweed is most abundant along the Duwamish River on industrial lands. It is also found in patches on the Puget Sound shoreline and on the shores of Vashon Island.

A native of southern Europe and western Asia, perennial pepperweed establishes rapidly and colonizes pastures, riparian habitats, and wet areas, as well as along roadsides, in rangelands and field crop situations. It degrades nesting habitat for wildlife and displaces desirable species in natural areas and hay meadows. It lowers digestibility and protein content of hay and inhibits grazing.

Biology and Morphology

Pepperweed generally grows 1 to 3 feet tall, but can reach up to 6 feet. It has many stems that emerge from a somewhat woody root crown with alternate, waxy leaves that have smooth or toothed margins and a prominent, whitish midvein. Basal leaves are lance-shaped and up to 12 inches long; they are attached by a stalk that can be almost as long as the leaf blade. Stem leaves are smaller, with shorter stalks. Perennial pepperweed's delicate, milky white flowers, which are sometimes collected for dry flower arrangement, grow in dense, rounded clusters at branch tips. Plants flower from June through September, producing small (1/16 inch) round or egg-shaped fruits. This plant spreads through profuse seed production and extensive, creeping roots. It has adapted to a wide range of habitats.

If you find perennial pepperweed in King County, please notify us through our online infestation form.

To find out where we have records of this weed in King County, use our interactive noxious weed map and search for perennial pepperweed.

For more information about perennial pepperweed, please follow this link to the WA State Noxious Weed Control Board.

Perennial pepperweed photos - click thumbnail for larger image