Yellow (or Common) Toadflax

Yellow Toadflax (Linaria vulgaris)

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Management Category

Synonyms

Common toadflax, butter and eggs, wild snapdragon

ID Characteristics

General: Yellow toadflax is a perennial forb.

Flowers: Bright yellow “snapdragon-like” flowers. Yellow toadflax flowers are arranged in groups (called racemes) at the ends of each branch. The yellow flowers have orange colouring on the throat. Flowers are 2 – 3.5 cm long.

Stem: Are erect, light-green, and unbranched. The stems can grow 0.15 – 1.0 m tall. Mature plants can have as many as 25 stems.

Leaves: The soft, lance-shaped, and pale green leaves are attached directly to the stem. The leaves are up to 10 cm long and grow in an alternate pattern along the stem.

Fruit: Egg-shaped capsules (5 – 10 mm long) contain many seeds that have broad wings ( about 2 mm wide).

Roots: Taproots (up to 1 m deep) with lateral creeping roots.

Similar Species

Invasive

Dalmatian-Toadflax-flowers-e1725403550458

Dalmatian toadflax (Linaria dalmatica) has broad, heart-shaped leaves and a woody stem.

Leafy-Spurge-plant-in-field-2-scaled-e1725403434847

Leafy spurge (Euphorbia esula) stems exude a milky latex when broken.

Non-invasive (exotic)

Snapdragons (Antirrhinum majus): This plant has very similarly-shaped flowers that can be many colours including yellow. Snapdragons don’t have the characteristic spur on the back of the flowers that Yellow or Common Toadflax do.

Habitat and Origin

Yellow toadflax was introduced from Europe and Asia in the mid-1800s as an ornamental garden plant. It was also used to make dye and folk remedies.

Yellow toadflax can be found in well-drained, open, low-elevation forests and grasslands. It is most commonly found in gravelly soil on roadsides, railroads, pastures, cultivated fields, and clear-cuts.

How it Spreads

Yellow toadflax reproduces through seed and vegetatively, via root segments. A mature plant can produce up to 30, 000 seeds annually and they can remain viable in the soil for up to ten years. Root fragments as short as 1 cm can grow into a full plant the following year.

Yellow toadflax can spread locally via vegetative reproduction through the root systems, but long-distance dispersal occurs through the transport of seeds. The wind primarily carries seeds, but water, animals, and humans (via clothing, equipment, and vehicles) may also spread the seeds.

Impacts

Ecological:

Toxic to wildlife.
Competes with native plants.
Reduces biodiversity.

Economic:

Reduces foraging area for livestock.
Alternative host for plant diseases like cucumber mosaic virus and broad bean wilt virus.

Prevent the Spread

Yellow toadflax is found in the Sea to Sky region and its distribution is beyond landscape-level control. When yellow toadflax is present at high-priority locations and negatively impacting them, their control is considered a high priority.

Otherwise, the goal is to prevent it from spreading to new (uninfested) areas, and to control it where possible to limit its impact on biodiversity.

Learn to identify yellow toadflax: use the images presented on this page to learn how to identify yellow toadflax.

What to do if you spot it: You can report any yellow toadflax sighting by visiting our reporting page.

DO:

Regularly monitor properties for weed infestations.
Ensure soil and gravel are uncontaminated before transport.
Check wildflower mixes to ensure that they do not contain yellow toadflax.
Ensure that plants are disposed of in a garbage bag if found in floral arrangements to prevent seeds from spreading.
Ensure plants (particularly flowering heads or root fragments) are bagged or covered to prevent spread during transport to designated disposal sites (e.g. landfill).
Minimize soil disturbances (e.g. use grazing plans that prevent soil exposure from overgrazing), and use seed mixes with dense, early colonization (e.g. alfalfa or barley) to re-vegetate exposed soil and resist invasion.

DO NOT:

Unload, park or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles, or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
Plant yellow toadflax in a garden, no matter how well-contained its enclosure may seem.
Move soil that has been contaminated with yellow toadflax.
Compost yellow toadflax.

Control

Mechanical

Hand-pulling is effective, especially in coarse-textured soils where roots can be removed easily (plants will regrow if root mass remains in the soil). Cutting, mowing or burning is not recommended because it does not kill the plant, and encourage regrowth. Any plant material that is removed should be placed in a plastic bag and disposed of at the landfill.

Chemical

Difficult to manage with herbicides. Herbicides should be applied during flowering when carbohydrate reserves in the root are at their lowest. Dicamba and picloram (with or without 2,4-D) have been effective in some situations; however, picloram is not suitable for wet, coastal soils. We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial, and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.

Biological

Five species occur in BC that could be used for yellow toadflax biocontrol: Brachypterolus pulicarius (beetle), Calophasia lunula (moth), Eteobalea intermediella (moth), Gymnaetron antirrhini (weevil), and Mecinus janthinus (beetle).