The Collaborative International Dictionary
Hellebore \Hel"le*bore\, n. [L. helleborus, elleborus, Gr. ?, ?; cf. F. hell['e]bore, ell['e]bore.]
(Bot.) A genus of perennial herbs ( Helleborus) of the Crowfoot family, mostly having powerfully cathartic and even poisonous qualities. Helleborus niger is the European black hellebore, or Christmas rose, blossoming in winter or earliest spring. Helleborus officinalis was the officinal hellebore of the ancients.
(Bot.) Any plant of several species of the poisonous liliaceous genus Veratrum, especially Veratrum album and Veratrum viride, both called white hellebore.
Wikipedia
Helleborus niger, commonly called Christmas rose or black hellebore, is an evergreen perennial flowering plant in the buttercup family, Ranunculaceae. It is poisonous.
Although the flowers resemble wild roses (and despite its common name), Christmas rose does not belong to the rose family ( Rosaceae).