Linaria dalmatica (L.) Mill.
Dalmatian toadflax is native to western Asia and southeastern Europe. It was introduced to the United States late in the nineteenth century, and has spread across much of the western United States and Canada, invading rangelands, disturbed areas, and natural habitats.
Plants: These robust plants put down roots as deep as 6' (1.8 m) underground. Stems are 16-39" (40-100 cm) high, mostly erect, often branched, stout, and round.
Leaves: alternate, in pairs or triplets on the upper part of the stem, attached directly to the stem (sessile), often bent, with sharp tips and broad bases. Leaves are leathery, hairless (glabrous), with a waxy layer that makes them somewhat bluish in color, and veins roughly parallel to leaf edges. Lower leaves are ⅜-1¾" (1-5 cm) long, and linear to lanceolate. Upper leaves are 1-2" (3-6 cm) × ⅜-1½" (1-4 cm), lanceolate to broadly ovate.
Flowers: Flowers are yellow, light yellow, or rarely, white. They appear on spiked racemes, and resemble snapdragons or butter and eggs. Each flower is up to 2" (5 cm) across, and has two “lips” and an orange hairy throat which offers nectar to pollinators.
Fruits: Seed capsules are round, less than ¼" (7.6 mm) in diameter, each containing two seed-filled chambers. A single plant produces 500,000 seeds, and if that isn’t enough, its extensive root system allows it to survive fire and attempts at eradication.
Edibility: Poisonous. Toxic to livestock in large quantities.
Linaria dalmatica at Minnesota Wildflowers
Linaria dalmatica on gobotany.nativeplanttrust.org
Linaria dalmatica on agri.nv.gov
Linaria dalmatica at the Bugwood Wiki
Linaria dalmatica at cabi.org’s Invasive Species Compendium
Linaria dalmatica on the USDA Forest Service's Fire Effects Information Database
Linaria dalmatica description by Thomas H. Kent, last updated 25 May 2020.