Common toadflax (Linaria vulgaris) is a perennial that reproduces primarily through an extensive root system. It was introduced from Europe almost 100 years ago as an ornamental.
Stems are erect and usually unbranched. Toadflax can grow as tall as 1m but usually reaches only 30cm in height.
Leaves are long, thin and lance-shaped. They resemble Leafy Spurge but do not contain milky white sap.
Flowers and Fruit
Toadflax bears yellow snapdragon flowers with an orange spot on the throat in a spike at the ends of its stems. The seeds mature in a capsule and are black, winged and disc-shaped. The germination rate of toadflax seed is very low (typically less than 10% of seed is viable).
Toadflax prefers sandy or gravelly soil that is easy to push new creeping roots through. It is adapted to grow under almost any soil or climate conditions, however.
Once established, toadflax is almost impossible to eradicate due to its extensive root system. Its success in pasture situations is increased since it is unpalatable to livestock.
Watch for toadflax in wildflower mixes under its scientific name of Linaria vulgaris or a more common name of 'Spurred Snapdragon'. Never purchase wildflower mixtures that don't list all species on the label.
Hand-pulling is only effective in soft soils that allow for root removal. Repeated pulling or mowing will starve the root system, however. Several years of consistent treatment will be required to eradicate the plant.
Toadflax is well-designed to shed chemicals and resist herbicide damage. Often a homeowner will have to resort to applying high rates of glyphosate to kill all vegetation present, including the toadflax, and then re-establish turf after the infestation is eradicated.
The seed-eating weevil Rhinusa antirrhini is well-established in the Grande Prairie area and can often be found feeding on toadflax seedheads.