Melampyrum

(cowwheat), a genus of annual hemiparasitic herbs of the family Scrophulariaceae. The leaves are green, opposite, and usually lanceolate. The flowers are yellow or, less commonly, pink; they form in the axils of large, often brightly colored bracts. The inflorescences are spikelike or racemose. The calyx is tubular and has four lobes; the corolla has two lips. There are four stamens. The fruit is a flattened pod, with one to four large seeds. There are approximately 30 species, distributed in the temperate zones of the northern hemisphere. Sixteen species are found in the USSR, growing in thickets, closed kettled valleys, clearings, damp fields, and meadows, as well as along forest edges. The most widespread species are Melampyrum nemorosum, M. pratense, and field cowwheat (M. arvense). Field cowwheat grows as a weed among crops and produces nectar. The seeds of many species contain the glucoside rhinantin and are poisonous to livestock.