Annual, biennial or perennial herbs without chlorophyll, parasitic upon the roots of other flowering plants. Stems erect, with alternate scale lvs crowded towards the base. Infl. usually a terminal spike or raceme, rarely fls solitary or in panicles. Fls bracteate, ☿, zygomorphic. Calyx ± tubular, 4-5-lobed or -toothed, irregularly split, forming 2 lips or nearly regular and cup-shaped. Corolla 5-lobed, often curved, 2-lipped to nearly regular; lobes imbricate. Stamens 4, didynamous, the fifth (adaxial) stamen reduced to a staminode or 0. Ovary superior, 1-locular, with 2-4 parietal placentas; ovules numerous; stigma ± 2-lobed. Fr. a loculicidal capsule. Seeds small, usually numerous, with minute embryo, endospermic.