Viburnum opulus (Gueler-rose, Water Elder) is a species of Viburnum, native to Europe and Asia. Some botanists also treat the closely related North American species Viburnum trilobum as a variety of it (as Viburnum opulus var. americanum Ait.), or a subspecies, Viburnum opulus subsp. trilobum (Marshall) Clausen. The name appears to have originated because a popular cultivar, the Snowball tree (see Cultivation and uses) supposedly first originated in the Dutch province of Guelderland.