Native Range

Eurasia

Appearance

Yellow toadflax is an erect, herbaceous perennial typically growing numerous stems 1–3 ft (0.3–1 m) tall from a taproot with spreading lateral roots. Leaves are alternate, green, pointed at both ends, and may have small petiole-like stalks. Older leaves are narrow and typically 1–2 in (2½–5 cm) long with a large central vein on the underside. Flowers are pale yellow and snapdragon-like with an obvious upper and lower lip and a spur pointing downward. Each has a fuzzy, bright orange throat. Flowers occur in spiked clusters at the top of the stem. Each flower produces an oval capsule fruit holding 10–40 viable, flat, disc-shaped seeds.

Impact

Because yellow toadflax competes aggressively for light, water, and nutrients, it can displace native and/or more desirable plant species in natural areas. Yellow toadflax also affects cropland and is a serious management concern on both cultivated and uncultivated sites. Large yellow toadflax infestations have caused economic injury to crops as diverse as grain, oil seed, berries/small fruits, and oil mint.

Reference

Sing, S.E., R.A. De Clerck-Floate, C.B. Randall, S.M. Ward, and I. Toševski. 2022. Toadflaxes (Linaria spp.): 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-2022-29-TOADFLAXES-P. https://bugwoodcloud.org/resource/files/27418.pdf

Resources

• Element Stewardship Abstract - The Nature Conservancy
• Weed Field Guide - USDA Forest Service

Selected Images

Maps

Invasive Listing Sources

• Alaska Noxious Weeds
• Alberta Weed Control Act
• California Invasive Plant Council
• City of Ann Arbor Michigan Parks and Recreation
• Colorado Noxious Weeds
• Idaho Noxious Weeds
• Invasive Plant Species of West Virginia
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• Montana Noxious Weeds
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Native Plant Society of Oregon, 2008
• Nevada Noxious Weeds
• New Mexico Noxious Weeds
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• North Dakota Noxious Weeds
• 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
• 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