Japanese snowball shrub, Viburnum plicatum var. plicatum, has large showy clusters of sterile flowers.
Description Viburnum plicatum is a small, up to 10 ft (3 m) tall, deciduous shrub with branches that spread horizontally and overlap each other. Mature shrubs are often wider than tall. The dark green leaves are toothed on the edges, pubescent beneath, and about 4 in (10 cm) long, turning purple-brown to dull red in autumn. Viburnum plicatum produces flat topped or rounded clusters (cymes) of white flowers in two rows along the branches. The flower clusters are held conspicuously above the branches on two-inch (5 cm) stems, giving them a layered effect, which makes them all the more showy. The individual flowers within a cyme may be small and fertile, or large and sterile. Fruits (when produced) are red, ripening to blue-black.
Doublefile viburnum (Viburnum plicatum var. tomentosa) is a naturally occurring plant that produces flat-topped cymes (flower clusters) with a ring of large, sterile flowers surrounding a center of small, fertile flowers, much like the “lace-cap” hydrangeas. The flower clusters may be up to 6 in (15 cm) across, and are held firmly above the branches. The outer, sterile flowers within the cluster can be an inch (2.5 cm) or more in diameter, and the inner, fertile flowers much smaller. The fertile flowers go on to produce egg shaped fruits and viable seed.
Japanese snowball (Viburnum plicatum var. plicatum) is a sterile variety of garden origin that was selected by gardeners from the wild species before the wild species was even known to the scientific community. It produces only the larger sterile flowers, and their weight causes the cymes to droop a bit, resulting in a less layered, and a somewhat less attractive appearance. The flowers come on 2-3 weeks later than V. p. var. tomentosum, and of course, Japanese snowball does not produce fruit.
Flower clusters arranged in two parallel lines is characteristic of the doublefile viburnum.
Both varieties come in many beautiful and useful cultivars, but there are more cultivars available of doublefile viburnum than of the sterile Japanese snowball. Doublefile viburnum cultivars include dwarfs no more than 18 in (50 cm) high; some with pink flowers; some with different shaped leaves, variegated leaves or leaves that are especially colorful in fall; and others with varying growth habits. One of the most popular, and widely available, is ‘Mariesii’, with distinctly tiered branching and larger flowers which reign higher above the foliage. ‘Shasta’ has much larger flowers and gets only 6 ft (2 m) tall with a wide-spreading habit that’s perfect for smaller gardens. Among popular cultivars of Japanese snowball are ‘Roseum’ with pink tinted flowers, and ‘Grandiflorum’ with larger flower clusters up to 4 in (10 cm) across.
The wild species, Viburnum plicatum var. tomentosa, grows in open woodlands in Japan and China, and was introduced to Western gardeners in 1865. The garden-origin form, V. p. var. plicata was first brought to the West in 1844 by the Scottish botanist and plant hunter, Robert Fortune, who was famous for introducing tea plants from China to Great Britain.
Both varieties respond well to pruning and may be cut back severely if necessary to maintain the horizontal tiered branching that makes them so distinctive. Light: Grow doublefile and Japanese snowball viburnums in dappled shade to full sun. Moisture: Both varieties like a moist, but well drained soil. They do not do well in clayey, poorly drained soils. They should be given supplemental watering during hot summers. Hardiness: USDA Zones 5-8. Doublefile viburnum and Japanese snowball will need shady, relatively cool positions to be grown in zone 8. Doublefile viburnum may be hardy to zone 4 in protected positions. Japanese snowball is less cold hardy than doublefile, and survives most winters only to zone 6. Propagation: Young, fast growing tip cuttings can be rooted easily, especially under mist.
Branches of a Japanese snowball bush hang heavy with flower clusters in late spring.
Like other viburnums, doublefile viburnum and its cousin Japanese snowball viburnum are useful in shrub borders and hedges, but they also make outstanding specimen shrubs. In springtime the show is horizontal branches, adorned with lacy snowballs of white flowers standing atop the branches, and in fall, wine-red leaves drooping from those stratified tiers. When in bloom, doublefile viburnum is unsurpassed among shrubs in its beauty, and deserves a special place in the landscape.
The shiny blue-black fruits are beautiful, but usually don’t last very long as they are relished by birds and other wildlife.
The nomenclatural type of a species is the species, subspecies, variety or form to which the scientific name of the species was first applied. The type of Viburnum plicatum is Viburnum plicatum var. plicatum. One would expect that the type of a species would be the natural, wild form, and not some garden-selected variety of the natural wild form. However, the sterile, garden-origin plant, Japanese snowball, was actually named before the wild species, doublefile viburnum, and it was named Viburnum plicatum. Later, when the natural, wild form was discovered by the botanists, and they realized that it was actually the same species, but clearly a different variety, they could not name it var. plicata, but had to come up with a new name. The rule of priority in botanical nomenclature requires that the first named subspecies, variety or form of a species gets the designation of “type”, and if other subspecies, varieties or forms of the same species are subsequently discovered, they must be given a new subspecies, variety or form name. In this case, the trinomial, Viburnum plicatum var. tomentosum, refers to the natural, wild species. Confused? Take a look at Floridata’s discussion of how plants get their scientific names.
We like viburnums (aka arrowwoods) here at Floridata. And with good reason. All of them are eminently manageable shrubs or small trees with opposite leaves and pretty flowers in showy terminal clusters. They are carefree and easy to grow in most any soil. The cultivated species are among the most popular of garden shrubs, offering attractive flowers in spring, as well as colorful foliage and wildlife friendly fruits in fall. We’ve profiled nine species of viburnums so far. Only 140 to go!