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 has been used medicinally and as a dye and can harbor cucumber mosaic and broad bean wilt viruses. Both species are native to the Mediterranean region. Compete poorly with established vegetation for soil moisture. Seedlings that have lost their cotyledons resemble new shoots from roots.