Native Range

Europe and Asia

Appearance

Hoary cress is a perennial forb growing from an extensive creeping root system. Rosette leaves are up to 4 in (10 cm) long with short stalks. They are grayish-green, scattered to densely hairy, and can have smooth or toothed margins. Stems grow 1–2 ft (30–60 cm) tall with multiple stems arising from the same root system. Stem leaves are alternate, have only scattered hairs, are somewhat smaller than rosette leaves, and have two lobes that clasp the stem. Flowers are produced in large clusters at the tips of branches. Each flower is ≤¼ in (½ cm) across and has four petals and six stamens. Fruits are flattened, upside down heart-shaped pods up to [ in (S cm) long. Each pod contains two small, reddish-brown seeds.

Impact

Hoary cress is considered one of the worst weeds of agriculture in several parts of the world. It reduces pasture and crop production and is an alternate host for several important crop pests worldwide. It is mildly toxic to livestock, especially when large amounts are digested. Grazing animals exposed to hoary cress reportedly have tainted milk or meat up to a week after exposure. Hoary cress displaces native plant species, alters natural food webs, and may increase streamside soil erosion.

Reference

Littlefield, J., C.B. Randall and J. Milan. 2023. Hoary Cress (Lepidium draba): History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2023-31- HOARY CRESS-P. https://bugwoodcloud.org/resource/files/27962.pdf

Resources

• Element Stewardship Abstract - The Nature Conservancy
• Federal Noxious Weed Disseminules of the U.S. - USDA-APHIS
• Weed of the Week - USDA Forest Service
• Weed Field Guide - USDA Forest Service

Selected Images

Maps

Invasive Listing Sources

• Alaska Noxious Weeds
• Alberta Weed Control Act
• Arizona Noxious Weeds
• California Invasive Plant Council
• California Noxious Weeds
• Colorado Noxious Weeds
• Idaho Noxious Weeds
• Iowa Noxious Weeds
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
• Kansas Noxious Weeds
• Michigan Noxious Weeds
• Montana Noxious Weeds
• Nevada Noxious Weeds
• New Mexico Noxious Weeds
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• Ohio Noxious Weeds
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• South Dakota Noxious Weeds
• Utah Noxious Weeds - Contain
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States
• Wyoming Noxious Weeds

References