Linaria vulgaris, commonly known as Yellow Toadflax, has quickly become a widespread invasive weed in North America since its introduction as an ornamental flowering plant over 100 years ago.
It sprouts primarily from rhizomatous roots, and because of this, populations appear in dense clusters which easily overtake neighbouring plants. Eliminating a Toadflax infestation may require several years of intensive root-removal.
Yellow Toadflax is easily identifiable due its single, waxy stem, with heart-shaped leaves near its base. The flowers resemble Snapdragons, with a sharp spike protruding from the bottom. Their off-white colour with a rich yellow centre has earned them the common nickname “Butter and Eggs”.
Here is a fact sheet provided by the Alberta Invasive Species Council
Yellow Toadflax Image from Alberta Invasive Species Council