YELLOW TOADFLAX (LINARIA VULGARIS)
Robust, branched perennial growing up to 60cm in height. Each plant may have 1-25 flowering stems that bloom from May through August. Flowers are bright yellow with a long spur, resembling snapdragons. Leaves are pale green, soft, and lance-shaped (pointed at both ends). There is a main taproot and several creeping stems that produce new plants. Seeds are winged and angular and borne in round capsules. It is similar to Dalmatian toadflax (linaria dalmatica), but the leaves of Dalmatian toadflax are rounder, shorter, and clasp the stem.
Habitat and Ecology
This species colonizes disturbed areas and open grasslands. It prefers coarse, well-drained soil, dry summers and low vegetation cover.
The glucoside in this plant is somewhat poisonous to livestock, although poisonings are rare as the plant is not palatable. Yellow toadflax competes with native grasses and forbs, changing species composition and reducing biodiversity of natural plant communities. It can also reduce the forage production of rangelands.
Five biocontrol agents for yellow toadflax occur in BC. Cutting plants will reduce seed spread but not kill the plant. Hand pulling when plants are young can be effective in destroying new populations, especially if done repeatedly. Plants should be pulled a few weeks after they emerge in spring to kill them before the lateral roots grow. Mowing does not kill the plant, but can reduce seed production. This plant is difficult to manage with herbicides; 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: Wendy VanDyk Evans, Bugwood.org