Perennial Pepperweed | Nebraska Invasive Species Council

Credit: Steve Dewey, Utah State University, Bugwood.org

General Information

Species Name: Lepidium latifolium

Also Known As: broadleaf pepperweed, tall whitetop, giant whitetop

Family: Brassicaceae (Mustard)

Growth Form: Forb

Life Span: Perennial

Flowering Dates: June-September

Origin: Eurasia

Toxic: No

Noxious: No

Why Is It Invasive?

Perennial pepperweed is an invasive plant that can form dense monocultures and displace native plants and desirable forage. Woody stems also degrade nesting habitat for wildlife.

What Does It Look Like?

Flowers

Flowers are white and have 4 spatula-shaped petals. They grow in clusters at the tips of stems.

Leaves

Leaves are alternately arranged about the stem. They are waxy and may have smooth or toothed margins. They range in color from green to grayish green.

Stems

Stems are upright and semi-woody. Stems emerge from a woody base.

Seeds

Round, flattened, and somewhat hairy. Reddish-brown in color.

Photos

Perennial pepperweed with small white flowers against a solid blue background.

Credit: Steve Dewey, Utah State University, Bugwood.org

Field of perennial pepperweed with green vegetation under a hazy sky.

Credit: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Small white flowers bloom on a green stem, surrounded by a blurred green background.

Credit: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Green leafy perennial pepperweed with narrow stems in a dense grassy setting.

Credit: Barry Rice, sarracenia.com, Bugwood.org

Small, oval, orange-brown seeds against a purple background with a scale indicating 1 mm.

Credit: Steve Hurst, USDA NRCS PLANTS Database, Bugwood.org

Perennial pepperweed with small, clustered blossoms and green stems in a rocky outdoor setting.

Credit: Mary Ellen (Mel) Harte, Bugwood.org

Cows standing in tall perennial pepperweed on a sunny day, with scattered trees in the background.

Credit: L.L. Berry, Bugwood.org

Where Does It Grow?

Perennial pepperweed prefers wet conditions and can be found in ditches, salt marshes, irrigation channels, rangeland habitats, wetlands, and disturbed sites. It is widespread throughout the United States.

How Does It Spread?

Perennial pepperweed reproduces through seed, rhizomes, and root fragments. Creeping rhizomes may extend up to 6 feet away from the parent plant. Seeds can spread through natural causes or human vectors, including contaminated agricultural shipments and by attaching to clothing, shoes, pets, and equipment. Perennial pepperweed first arrived to North America in the early 1900s as a contaminant in sugar beet seed.

How Do I Control It?

Mechanical

Due to perennial pepperweed's brittle roots and ability to reproduce through root fragments, manual removal is not recommended and can actually help spread the plant. Spring mowing, in combination with other control methods, can be effective.

Please contact your county weed control authority to determine appropriate removal methods.

Cultural

Plant competitive and desirable vegetation to help prevent against perennial pepperweed establishment. Most livestock will not graze on perennial pepperweed and there have been cases of toxicosis linked to grazing in equines. Permitting goats to graze on perennial pepperweed infested fields may aid in control. When buying hay or forage, check to make sure it is weed-free certified.

One way that invasive plant seeds and fragments can spread is in soil. Sometimes plants are planted purposefully. You can prevent the spread of invasive plants.

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