Viburnum opulus (Guelder-rose) 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. 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 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. It is commonly grown as an ornamental plant for its flowers and berries, growing best on moist, moderately alkaline soils, though tolerating most soil types well. Several cultivars have been selected, including 'Snowball' ("Snowball Tree"), which has all the flowers of the sterile type; it is more conspicuous in flower but does not produce any fruit. Snowball bush is a name often given to Viburnum opulus for its white clusters of flowers that appear in spring. There is some confusion, as there are a few other bushes, including other members of the Viburnum genus, also referred to as "snowball bush". It is naturalised in North America, where it has been misleadingly re-named as "European Cranberrybush" (it is not a cranberry). The fruit is edible in small quantities, with a very acidic taste; it can be used to make jelly. It is however very mildly toxic, and may cause vomiting or diarrhoea if eaten in large amounts