musk thistle, nodding thistle
(Carduus nutans L.)

Overview

Appearance

Carduus nutans is an herbaceous, biennial plant that grows to 6 ft. (1.8 m) tall. The stem has very spiny wings. Carduus species may hybridize with each other.

Foliage

Leaves are green and lanceolate to oblong-lanceolate. They are often pinnatifid and are very prickly. Leaves are usually sessile to slightly clasping. Basal leaves are 4-16 in. (10-40 cm) long. Leaf characteristics are variable across different varieties and subspecies.

Flowers

Showy, solitary, hemispherical, red to purple, disk flowers bloom from June to September. Phyllaries are spinetipped and overlap with several rows.

Fruit

Fruits are small achenes, 1.52 in. (45 mm) long, about 0.04 in. (1 mm) in diameter, including a white to light brown pappus. The seeds have longitudinal dotted stripes.

Ecological Threat

Carduus nutans invades a variety of disturbed areas. Pastures are particularly at risk because It is unpalatable to livestock. Once established it can spread rapidly due to high seed production (as much as 120,000 seed per plant). Carduus nutans is native to Western Europe and was accidentally introduced into the United States in the early 1900s.

Resources

• Biological Control of Invasive Plants in the Eastern United States - USDA Forest Service
• Southeast Exotic Pest Plant Council Invasive Plant Manual - SE-EPPC
• Fire Effects Information System - USDA Forest Service
• Weeds Gone Wild: Alien Plant Invaders of Natural Areas - Plant Conservation Alliance
• Element Stewardship Abstract - The Nature Conservancy
• Weed of the Week - USDA Forest Service
• Weed Field Guides - USDA Forest Service

Selected Images

Maps

Invasive Listing Sources

• Alabama Invasive Plant Council
• Alberta Weed Control Act
• Arizona Noxious Weeds
• California Invasive Plant Council
• California Noxious Weeds
• Colorado Noxious Weeds
• Commonwealth of Pennsylvania, Department of Conservation and Natural Resources, 1994.
• Georgia Exotic Pest Plant Council - Category 3
• Hoffman, R. & K. Kearns, Eds. 1997. Wisconsin manual of control recommendations for ecologically invasive plants. Wisconsin Dept. Natural Resources, Bureau of Endangered Resources. Madison, Wisconsin. 102pp.
• Idaho Noxious Weeds
• Illinois Noxious Weeds
• Indiana Invasive Species Council - Invasive Plant List
• Indiana Terrestrial Plant Rule
• Iowa Forest Invasive Plants
• 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
• Kentucky Exotic Pest Plant Council - Severe Threat
• Maryland Code and Regulations Noxious Weed & Seed Law
• Maryland Department of Natural Resources Policy: Restriction on Planting Exotic Invasive Plants
• Maryland Invasive Species Council - Invasive Species of Concern in Maryland
• Maryland Noxious Weeds
• Michigan Noxious Weeds
• Missouri Noxious Weeds
• Missouri SRISP Species List
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Nebraska Noxious Weeds
• Nevada Noxious Weeds
• New Mexico Noxious Weeds
• Non-Native Invasive Plants of Arlington County, Virginia
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• North Carolina Noxious Weeds
• North Dakota Noxious Weeds
• Ohio Noxious Weeds
• Oklahoma Noxious Weeds
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• Pennsylvania Department of Conservation and Natural Resources Invasive Plants
• Pennsylvania Noxious Weeds
• Pennsylvania Regulations for Controlled Plants and Noxious Weeds
• South Carolina Exotic Pest Plant Council
• Utah Noxious Weeds - Contain
• Virginia Invasive Species Management Plan 2012
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States
• West Virginia Department of Agriculture Regulations Governing the Distribution of Plant Materials
• West Virginia Noxious Weeds
• Wisconsin Noxious Weeds
• Wisconsin's Invasive species rule – NR 40
• Wyoming Noxious Weeds

References