Lepidium latifolium

Keys to Identification

• Perennial pepperweed has dense clusters of white flowers that appear in early summer
• The leaves and stem are covered with a waxy layer

This information courtesy of the Colorado Natural Areas Program

Family

Mustard (Brassicaceae)

Other Names

Tall whitetop, broad-leaved peppergrass, Virginia pepperweed.

USDA Code

LELA2

Legal Status

Colorado Noxious Weed List B

Identification

Lifecycle

Perennial

Growth form

Forb

Flower

White flowers are packed in dense clusters near the ends of branches. May-Aug.

Seeds/Fruit

Fruits are nearly round, about 0.1 in wide and usually sparsely hairy.

Leaves

Leaves are alternate, lance-shaped, entire to toothed, bright-green to gray-green, and don’t have clasping bases. The basal leaves are larger than the upper leaves.

Stems

Mature plants are 1-3 ft tall.

Roots

Perennial pepperweed can form deep-seated rootstocks.

Seedling

The leaves and stem are covered with a waxy layer (Whitson et al 1996).

Similar Species

Exotics

Hoary cress (Cardaria draba), leaves have clasping bases, perennial pepperweed can also be distinguished by its waxy appearance.

Natives

None known.

Impacts

Agricultural

Perennial pepperweed invades irrigated pastures, cropland, and native meadows (FEIS 1998).

Ecological

Perennial pepperweed is an aggressive colonizer of riparian habitats. It establishes rapidly and can eliminate competing vegetation (FEIS 1998).

Habitat and Distribution

General requirements

Perennial pepperweed is most often found in open, unshaded areas on disturbed, and often saline soils.

Distribution

Perennial pepperweed is locally common in riparian areas, marshy floodplains, valley bottoms, and seasonally wet areas from 5,500 to 9,000 ft. Perennial pepperweed is found in similar environments throughout much of the western U.S.

Historical

Introduced from Eurasia.

Biology/Ecology

Life cycle

Dense flower clusters appear in early summer and continue through August.

Mode of reproduction

Mainly by spreading rhizomes, and can be an aggressive colonizer of disturbed areas (FEIS 1998).

Seed production

Perennial pepperweed produces an abundance of highly germinable seeds. Seed production is from June to August.

Seed bank

Seeds have no apparent dormancy.

Dispersal

Seeds drop from the plant or travel short distances by wind/water.

References

FEIS – Fire Effects Information System [Online] (1996, September). Prescribed Fire and Fire Effects Research Work Unit, Rocky Mountain Research Station (producer), US Forest Service. Available: www.fs.fed.us/database/feis/ [1998,March 12]

Whitson, T.D.(ed.), L.C. Burrill, S.A. Dewey, D.W. Cudney, B.E. Nelson, R.D. Lee, R. Parker. 1996. Perennial pepperweed. Weeds of the West. Western Society of Weed Science, in cooperation with the Western United States Land Grant Universities Cooperative Extension Services, Newark CA. pg. 230.