Viburnum opulus (Guelder-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.
It is a deciduous shrub growing to 4-5 m tall. The leaves are opposite, three-lobed, 5-10 cm long and broad, with a rounded base and coarsely serrated margins; they are superficially similar to the leaves of some maples, most easily distinguished by their somewhat wrinkled surface with impressed leaf venation. The leaf buds are green, with are valvate bud scales.
The hermaphrodite flowers are white, produced in corymbs 4-11 cm diameter at the top of the stems; each corymb comprises a ring of outer sterile flowers 1.5-2 cm diameter with conspicuous petals, surrounding a center of small (5 mm), fertile flowers; the flowers are produced in early summer, and pollinated by insects. The fruit is a globose bright red drupe 7-10 mm diameter, containing a single seed. The seeds are dispersed when birds eat the fruit, then deposit the seeds in another location in their droppings.