Annual or perennial hemi-parasitic herbs, rarely shrubs. Leaves alternate, lowest opposite, entire to pinnately dissected. Inflorescence a spike or raceme, bracteate; bracts gradually differing from leaves upwards, becoming more dissected and often coloured upwards. Flowers zygomorphic, bisexual; sepals united to form 2 or 4-lobed tube; petals united to form a tube, 2-lipped, upper lip folded downwards forming a beak, lower lip highly reduced to 3 small teeth or 3-lobed up to length of beak and often contiguous with a 3-saccate ventral pouch extending along the corolla tube; stamens 4, in 2 pair, 1 pair longer than the other; anthers with 2 pollen sacs; stigma capitate or bilobed. Fruit an ovoid loculicidal capsule. Seeds numerous, ovoid, pyramidal, oblong or trapezoidal with reticulate and loose- or tight-fitting seed coat.
c. 200 species mostly in western North America but extending throughout North America and to the Andes and also in northern Asia; 2 species recorded in Australia.