General: Dalmatian Toadflax is a short-lived perennial; individual plants can live 3 – 5 years.
Flowers: Are bright yellow and snapdragon-like, with an orange throat.
Stem: Are narrow and upright, originating from a stocky, woody base that can grow up to 1 m.
Leaves: Are alternate, and clasping on the stem. Dalmatian Toadflax leaves are heart-shaped, waxy and light green with a bluish cast.
Roots: Dalmatian Toadflax has rhizomes. The root system is perennial and spreading.
Yellow or Common Toadflax (Linaria vulgaris): This plant is of the same genus, and has similar yellow flowers. Dalmatian Toadflax leaves are clasping, shorter and more broad-based than Yellow Toadflax. Yellow Toadflax is also shorter (up to 60 cm tall).
Habitat and Origin
Origin: Dalmatian Toadflax is native to Western Asia as well as the Mediterranean region; it was introduced to North America in the late 19th century as a garden ornamental.
Habitat: Dalmatian Toadflax is most commonly found on sandy or gravely soil on roadsides, railroads, pastures, cultivated fields, rangelands and clear cuts. It is adapted to a wide variety of conditions: it thrives in poor, dry soils, but can also cause issues in high-quality soils. Dalmatian Toadflax does well in sunny to partly shaded conditions.
Dalmatian Toadflax is often associated with several other invasive species. For example, it appears to be spreading as Diffuse and Spotted Knapweed are controlled. Similarly, Dalmatian Toadflax has been observed on rangeland sites after biological control suppressed St. John’s Wort.
Propagation & Vectors of Spread
Dalmatian Toadflax reproduces by seed and vegetatively. One mature plant can produce up to 500,000 seeds each year, and seeds remain viable in the soil for up to 10 years.
It also reproduces vegetatively via creeping rhizomes, and from root fragments.
Dalmatian Toadflax seeds are extremely small so they can spread by the wind. Dried flower stalks and seeds can remain on the plant for up to 2 years, and the stalks easily break off and spread in the landscape. Seeds also mix with soil and can be transported in clothing, equipment or vehicles. Root fragments can create new plants, so improper plant disposal could also help spread Dalmatian Toadflax.
Ecological and Health Impacts
- Toxic to livestock (when consumed in significant amounts)
- Out-competes with native grasses, reduces biodiversity
- Displaces native species through its creeping root system
- Reduces the quality of rangelands
What Can I Do?
Dalmatian Toadflax is found in communities the Sea to Sky Region, so PREVENTION of further spread is key.
Learn to identify Dalmatian Toadflax: use the images presented in this profile page to learn how to identify this plant.
What to do if you spot it: You can report any sighting by clicking here.
- Regularly monitor properties for infestations.
- Avoid planting Dalmatian Toadflax
- Ensure soil and gravel are uncontaminated before transport
- Remove plant material from any equipment, vehicles, or clothing used in infested areas and wash equipment and vehicles at designated cleaning sites before leaving these areas.
- 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.
- Ensure plants (particularly flowering heads or root fragments) are bagged or covered to prevent spread during transport to designated disposal sites (e.g. landfill).
- Don’t 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 before leaving infested areas.
- Do not plant Dalmatian Toadflax, no matter how well-contained the area might seem.
- DO NOT COMPOST!
- Hand-pull new and small infestations before the plants set seed.
- Ensure you remove as much of the root system as possible.
- In the case of more mature infestations, mechanical control must be repeated annually for at least 10 years to exhaust the seed bank.
- Mowing is only effective to diminish seed production, but not to control the plant.
- Dalmatian Toadflax’s waxy leaves make the use of an oil or silicon-based surfactant necessary.
- Satisfactory control can also be achieved using dicamba; chlorsulphuron, glyphosate or imazapyr have also proven effective.
- Picloram can be effective, but it 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.
- Several biocontrol agents have been released in BC, most notably Mecinus janthinus, a black stem-boring weevil.
- Calophasia lunula, a moth, as well as Rhinusa antirrhini, another weevil, are also known biocontrol agents.
- Coastal Invasive Species Council, Dalmatian Toadflax, https://www.coastalisc.com/dalmatian-toadflax/
- Invasive Species Compendium, Linaria dalmatica, https://www.cabi.org/isc/datasheet/30827
- Invasive Species Council of BC, Dalmatian Toadflax, https://bcinvasives.ca/invasive-species/identify/invasive-plants/dalmatian-toadflax
- Lillooet Region Invasive Species Society, Dalmatian Toadflax, https://lriss.ca/species/dalmatian-toadflax-linaria-dalmatica
- Okanagan and Similkameen Invasive Species Society, Dalmatian Toadflax, http://www.oasiss.ca/pdfs/FACTSHEET_DT_updated%20May%202013.pdf
- Okanagan Invasive Species Online, Dalmatian Toadflax, https://www.oiso.ca/species/dalmatian-toadflax/
- US Department of Agriculture, Field Guide for Managing Dalmatian and Yellow Toadflaxes in the Southwest, https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5410111.pdf
- Washington State Noxious Weed Control Board, Dalmatian Toadflax, https://www.nwcb.wa.gov/weeds/dalmatian-toadflax