Herbaceous perennials, with creeping roots and showy yellow flowers, to 1.2 m tall. Plants are highly competitive for soil moisture with winter annuals and shallow-rooted perennials. Infestations often form large colonies, displacing desirable vegetation. On infested rangeland, livestock typically avoid grazing plants. Yellow toadflax was reportedly first introduced to North America from Europe, by a man named Ranstead, who accompanied William Penn to present day Pennsylvania in the late 1600s. Yellow toadflax has since widely escaped cultivation. Yellow toadflax has been used medicinally and as a dye and can harbor cucumber mosaic and broad bean wilt viruses. Numerous insects attack the toadflaxes;. Both species are native to the Mediterranean region.

SEEDLINGS : Compete poorly with established vegetation for soil moisture. Seedlings that have lost their cotyledons resemble new shoots from roots. Seedlings initially develop a taproot

MATURE PLANT:Stems typically branched near the top. Leaves primarily alternate, but crowded and often appearing opposite or whorled, especially near the bases of stems. Leaf margins entire. Aboveground parts die back to the ground in fall Stems erect, glabrous. Leaves sessile, ovate to lanceolate, 3-6 cm long, with pointed or long-tapered tips, +/- clasping at the base, stiff, typically ascending, glabrous, usually bluish-green and covered with a whitish film (glaucous).

ROOTS and UNDERGROUND STRUCTURES: Plants develop an extensive system of vertical and creeping lateral roots that produce new shoots. Root fragments can produce new plants. Roots can associate with vesicular-arbuscular mycorrhizae. Dalmatian toadflax roots can penetrate soil to depths of 2 m or more. Lateral roots are typically 5-20 cm below the soil surface and can extend outwards to 3.5 m in all directions

FRUITS and SEEDS: Capsules +/- round, 2-chambered, opening by irregular slits at the apex to release numerous black to brown seeds

HABITAT: Disturbed open sites, fields, pastures, degraded rangelands, roadsides, agronomic and perennial crops. Both species tolerate a broad range of climatic conditions and soil types.

PROPAGATION/PHENOLOGY: Reproduces by seed and vegetatively from creeping lateral roots. Most seed falls near the parent plant. Some seed disperses short distances with wind and to greater distances with water, soil movement, and by clinging to the feet, fur or feathers of animals. Seed production and viability is highly variable, depending on out-crossing and presence of pollinators. Seeds germinate in spring and fall when conditions become favorable. Germination occurs on the soil surface and to a depth of 3 cm. Plants can rapidly colonize a site by vegetative reproduction from creeping roots. Dalmation and yellow toadflax can hybridize Plants with 10-15 stems can produce up to 500,000 seeds, with an average of ~140-250 seeds per capsule. Seeds appear to require an after-ripening period of ~ 1-2 months. Seeds produced early in a season have a longer dormant period than seed produced later. Under field conditions, seed may remain viable for up to 10 years. Most seedlings emerge from within 5 mm of the soil surface. Germination is highest on open sites with compacted soils and little vegetation