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.