hellebore, name usually for plants of the genus Helleborus of the family Ranunculaceae (buttercup family), Eurasian perennials with attractive palmately divided leaves and flowers of various colors. Hellebores are noted for their early blooming, particularly the black hellebore or Christmas rose (H. niger), with evergreen leaves and white or greenish blossoms that resemble wild roses. Hellebores and other species have been used medicinally but are highly toxic. Species of the genus Veratrum—which are also poisonous and medicinal and which yield an insecticide—are variously known as false, or American, hellebore and white hellebore; they are unrelated plants of the family Liliaceae (lily family). Hellebore is classified in the division Magnoliophyta, class Magnoliopsida, order Ranunculales, family Ranunculaceae.

Member of either of two genera of poisonous herbaceous plants, Helleborus (buttercup family) and Veratrum (lily family). Some are grown as garden ornamentals. Helleborus consists of about 20 species of perennial plants native to Eurasia; most are nearly stemless, with thick roots and long-stalked, divided leaves and showy flowers. Veratrum contains about 45 species, better called false hellebores, native widely to damp areas of the Northern Hemisphere. They have simple leaves and clusters of small flowers.

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