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Perennial pepperweed Lepidium latifolium |
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Keys to Identification:
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This information courtesy of the Colorado Natural Areas Program Family: Brassicaceae (Mustard) 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. Seeds/Fruit: Fruits are nearly round, about 0.1 inch in diameter 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 feet tall. Roots: Perennial pepperweed can form deep-seated rootstocks. Other: 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 feet. It is found in big sagebrush (Artemisia tridentata) communities of the Piceance Basin of Colorado (FEIS 1998). Plant associates in these communities include twisted moss (Tortula ruralis) and desert goosefoot (Chenopodium pratericola) (FEIS 1998). Perennial pepperweed is found in similar environments throughout much of the western U.S. Historical: Perennial pepperweed was introduced from Eurasia. Biology/Ecology Life cycle: Dense flower clusters appear in early summer and continue through August. Mode of reproduction: Perennial pepperweed reproduces 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. Integrated Management Summary A combination of mechanical (cutting or pulling) and herbicide applications can provide effective control of perennial pepperweed. Plants should be cut or pulled during the flower bud stage. Herbicides should be applied to the recovering stems when they return to flower bud stage later the same year. References
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