common burdock, lesser burdock
(Arctium minus Bernh.)

Overview

Appearance

Arctium minus grows up to 6 ft. (1.8 m) tall. It is a biennial forb that occurs throughout the United States. First year plants form large rosettes. A stout flowering stalk is formed in the second year.

Foliage

Stem leaves are large, heart-shaped and very hairy on the undersides. Basal leaves are dark green, heart-shaped and up to 1 ft. (0.3 m) long.

Flowers

Flowering occurs in July to October, when pink to purple flowers develop. Flowers are enclosed in a prickly bur.

Fruit

One plant typically produces 15,000 seeds. It reproduces by seeds.

Ecological Threat

Arctium minus can become a problematic invader of pastures, hay fields and open prairie ecosystems. It acts as a secondary host for pathogens, such as powdery mildew and root rot, which affect economically important plants. Arctium minus is native to Europe and came to the United States via accidental introduction. Indirectly affects the development of economically important plants by hosting powdery mildew and root rot. Reduces the value of sheep’s wool due to the seed heads entangling in it. It is responsible for tainting milk products if grazed in large quantities.

Resources

• Weed Identification Guide - Virginia Tech
• Weed of the Week - USDA Forest Service

Selected Images

Maps

Invasive Listing Sources

• Alberta Weed Control Act
• City of Ann Arbor Michigan Parks and Recreation
• Colorado Noxious Weeds
• 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.
• Invasive Plant Association of Wisconsin
• Invasive Plant Species of West Virginia
• 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.
• Kentucky Exotic Pest Plant Council - Moderate Threat
• Missouri SRISP Species List
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Native Plant Society of Oregon, 2008
• Ohio Invasive Species Council
• WeedUS - Database of Plants Invading Natural Areas in the United States
• West Virginia Invasive Species Strategic Plan and Volunteer Guidelines 2014
• West Virginia Native Plant Society, Flora West Virginia Project, and West Virginia Curatorial Database System, September 3, 1999
• Wyoming Noxious Weeds

References