CORNUS. Dogwood. Widespread in North America, Europe and Asia. This is a sizeable group of shrubs and trees, including some of our best-loved ornamentals. The shrubby sorts have generally long, wandlike stems, often making broad thickets. Some of the trees have their branches arranged in horizontal tiers, giving a distinctly oriental effect. In either case, they have large pointed-oval leaves, normally paired along the stems and conspicuously veined. The flowers are small, clustered in many species like those of the viburnums. The white to red, blue or black berries which follow also resemble those of the viburnums. Several species have the true flowers clustered more tightly into a central ball, surrounded by large, usually white or pinkish bracts, which most gardeners see as the flower. Many are deciduous and among the most colorful of all trees and shrubs in the fall. All have attractive winter silhouettes, and some, like C. sibirica, extend the show with brightly painted bark. Sun or light shade, well drained, non-alkaline soil and regular watering except as described below. Their hardiness varies as described.