DALMATIAN TOADFLAX (LINARIA DALMATICA)
Robust, branched perennial growing up to 1.2m tall. Each plant may have 1-25 flowering stems that bloom from May through September. Flowers are bright yellow with a long spur, resembling snapdragons. Leaves are waxy, pale green, and alternate, generally clasping the stem. There is a main taproot and several creeping stems that produce new plants. Seeds are winged and angular and borne in round capsules. A similar species is yellow toadflax (Linaria vulgaris); yellow toadflax has leaves pointed on both ends and is usually smaller.
Habitat and Ecology
Dalmatian toadflax is adapted to a wide variety of conditions. It can be found on disturbed roadsides, fields, gardens, cultivated land, grasslands, and the grassland-forest transition. It spreads by seed and roots; a single plant can produce 500,000 seeds each year.
Dalmatian toadflax invades agricultural lands where low-tillage practices are carried out. Alkaloids in the plant make it toxic to livestock; however, it is not palatable so there are few reports of poisonings. This plant can form dense colonies through its creeping root systems, displacing native vegetation and altering the species composition of natural communities. Infestations reduce the quality of rangeland.
Five biocontrol agents, including beetles, weevils, and moths, occur in BC, and have reduced the population in parts of the province. Cutting plants reduces seed spread but does not kill the plant. Hand pulling when plants are young can be effective on new populations, but it can be difficult to hand pull older plants as the main taproot can grow 1.2m into the soil. Plants should be pulled a few weeks after they emerge in spring to kill them before the lateral roots grow. Herbicides are effective on this species; consult the BC Ministry of Agriculture, Food and Fisheries Crop Production Guides for recommendations. Burning is not recommended; it does not affect the underground roots and buds, can remove native plant competition, and can even stimulate root growth.
Province of British Columbia. 2002. Guide to Weeds in British Columbia.
USDA Fire Effects Information System http://www.feis-crs.org/beta/
Photo reference: L.L. Berry, Bugwood.org