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
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.
Other: The leaves and stem are covered with a waxy layer (Whitson et al 1996).
Exotics: Hoary cress (Cardaria draba), leaves have clasping bases, perennial pepperweed can also be distinguished by its waxy appearance.
Natives: None known.
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.
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.
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.