Viburnum L. (1753), Arrow-wood or Wayfaring Tree. In the family Adoxaceae (traditionally in the Caprifoliaceae), contains around 150 species distributed around the northern hemisphere.

Description Upright shrubs, or rarely small trees, to 10m. The leaves are opposite, deciduous or evergreen, and often toothed.
The flowers are small, white or pinkish, often scented, crowded into flat, rounded, or pyramidal heads, sometimes with sterile outer florets larger than the fertile inner ones. Sepals 5, inconspicuous. Petals usually 5, spreading, forming a radially symmetrical corolla, joined at the base to form a tube. Stamens 5. Ovary inferior, with 1 cell and 1 ovule; style 1. Pollination is by various insects. The fruits are berries with 1 hard, usually flattened seed.

Key Recognition Features The opposite leaves and the flat, pyramidal, or rounded heads of small flowers, followed by 1-seeded berries.

Evolution and Relationships Related to Sambucus and now included with it in the Adoxaceae. Enlarged, sterile florets very similar to those found in V. plicatum Thunb. and V. opulus L. are also found in Hydrangea; less similar ones in Scabiosa L. and of course in the Compositae. Viburnum is a large and diverse genus, with species that flower in winter, spring, or summer. It is divided into 9 sections. Section Thyrsosma includes the winter-flowering V. farreri Stearn and the commonly planted V. x bodnantense Aberc. ex Stearn, as well as V. erubescens Wall.
Section Lantana includes the wild European V. lantana L., called the wayfaring tree, as well as the scented V. carlesii Hemsl. and its hybrids. Section Pseudotinus includes the American V. lantanoides Michx., with enlarged outer florets. Section Pseudopulus includes V. plicatum Thunb. and the Chinese species with enlarged florets. Section Lentago includes the American V. lentago L., the sheep-berry.
Section Tinus includes the Mediterranean V. tinus L., the laurustinus, commonly planted in Victorian shrubberies, and also the Chinese evergreen V. davidii Franch. Section Megalotinus includes the evergreen Himalayan V. cylindricum D. Don. Section Odontotinus includes V. betulifolium Batal., grown for its spectacular autumn berries. Section Opulus includes V. opulus L., the guelder rose, and V. trilobum Marsh, the cranberry-bush.

Ecology and Geography In woods, fens, and scrub. Found in North America and southwards along the Andes to Chile, in Europe and North Africa, and in Asia eastwards to China, Japan, Java, and New Guinea.

Comment Selected forms of the common species V. opulus and V. plicatum have “snowball” flowers, in which all the flowers are sterile, forming a rounded head. Many species are grown for their fruit as much as for their flowers; some species have edible fruit, but many are poisonous. The spring-flowering V. carlesii and its hybrids are among the best-scented of all shrubs. Many species are notable for their straight shoots; V. acerifolium L. is the American arrowwood, and arrows made of V. lantana were found in 1991 with a neolithic man preserved in the ice of the Ötztal in the Alps.

Photograph: Viburnum plicatum Mariesii