Description from Flora of China
Herbs annual, biennial, or perennial parasites, without chlorophyll. Stems unbranched or sometimes branched. Leaves scalelike, spirally or subimbricately arranged. Inflorescences racemose, spicate, or subcapitate, rarely 1-flowered; bract 1, usually similar to leaves; bractlets 2, adnate to base of calyx or pedicel. Flowers bisexual, subsessile or pedicelled. Calyx tubular, cupular, or campanulate, (3 or)4-6-lobed, 2-6-parted, 6-toothed, or spathelike, sometimes absent or of 3 free sepals. Corolla bilabiate, usually curved, sometimes tubular-campanulate or funnelform with 5 subequal lobes; upper lip entire, emarginate, or 2-lobed; lower lip 3-lobed. Stamens 4, didynamous, inserted at base of corolla tube; filaments slender; anthers 2-celled, dehiscing longitudinally, sometimes 1 cell fertile and another sterile or reduced to spur. Pistil 2- or 3-carpellate; ovary superior; placentas 2-4 or 6(-10), parietal or sometimes axile at ovary base; ovules 2-4 or numerous, anatropous. Style long; stigma inflated, discoid, peltate, or 2-4-lobed. Capsule usually dehiscing loculicidally by 2 or 3(or 4) valves. Seeds minute, testa pitted or reticulate.
About 15 genera and 150 species: North Temperate regions, less represented in Africa, America, Asia, and Australia; nine genera and 42 species (nine endemic) in China.
Genera 1-4 are assigned to the tribe Orobancheae (inflorescences racemose or spicate, rarely branched or flowers solitary, borne well above soil surface; mechanical tissue in 1 or 2 rings), whereas genera 5-8 are placed in the tribe Gleadovieae Popov (inflorescences subcapitate or subcorymbose, borne near soil surface; mechanical tissue absent). Although Lathraea has traditionally been placed in the Orobanchaceae (see Beck in Engler, Pflanzenr. IV. 261(Heft 96): 1-348. 1930), more recent authors (e.g.,Tzvelev, Fl. URSS 23: 19-117. 1958; Webb, Fl. Europ. 3: 281. 1972; Teryokhin et al., Determinator of broomrapes of the USSR Flora. 1993; Yamazaki, Fl. Japan 3a: 373. 1993) exclude the genus from the Orobanchaceae and place it in the Scrophulariaceae. In fact, one of us, N. N. Tzvelev, believes that Lathraea should be placed near Tozzia Linnaeus of the Scrophulariaceae. The genus is tentatively placed here as a link with the Scrophulariaceae.
Zhang Zhiyun. 1990. Orobanchaceae. In: Wang Wentsai, ed., Fl. Reipubl. Popularis Sin. 69: 69-124.
(Authors: Zhang Zhi-yun; Nikolai N. Tzvelev)