Native Range

Asia, Africa, and Mediterranean Europe

Appearance

Rush skeletonweed is an herbaceous perennial typically growing 1–4 ft (0.3–1.2 m) tall from a deep and sometimes rhizomatous root system. Rosettes have deeply lobed, hairless leaves up to 5 in (13 cm) long. Stems are wiry, and their bottom portions are covered with stiff, golden-reddish and downward-pointing hairs. Stem leaves are alternate, small, narrow, and up to 4 in (10 cm) long. As flowering stems mature, stem leaves often wither; the remaining bare stems give the plant an overall skeleton appearance. Flower heads are ½ in (1¼ cm) across and consist of 9–12 yellow ray florets that produce seeds without fertilization. Seeds are small, brown, and topped by tufts of pappus. All parts of the plant exude a milky latex when damaged.

Impact

Rush skeletonweed is one of the most problematic exotic plant species in the Intermountain West of the USA. Because of its propensity to compete aggressively for light, water, and nutrients, rush skeletonweed dramatically reduces yields in agricultural crops (especially wheat), and it displaces native species in natural areas. Although young rosettes are nutritious and are often eaten by livestock and wildlife, cattle still prefer grasses to young rush skeletonweed, and older flowering stems of rush skeletonweed are not palatable to most domestic cattle and sheep. Consequently, grazing of infested pastures or rangeland often increases the amount of rush skeletonweed and decreases livestock production.

Reference

Milan, J., J. Littlefield, C.B. Randall, and J.E. Andreas. 2022. Rush Skeletonweed (Chondrilla juncea): 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-2022-13-RUSH SKELETONWEED-P. https://bugwoodcloud.org/resource/files/25240.pdf

Resources

• Weed of the Week - USDA Forest Service
• Weed Field Guide - USDA Forest Service

Selected Images

Maps

Invasive Listing Sources

• Alberta Weed Control Act
• Arizona Noxious Weeds
• California Invasive Plant Council
• California Noxious Weeds
• Colorado Noxious Weeds
• Idaho 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.
• Montana Noxious Weeds
• Nevada EDRR
• Nevada Noxious Weeds
• New Invaders of the Southwest
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• Utah Noxious Weeds - Control
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States

References