sourwood, (species Oxydendrum arboreum), deciduous ornamental tree, of the heath family (Ericaceae), native to southeastern North America. It grows to about 23 metres (75 feet) in height. The bitter-tasting leaves are alternate, stalked, rather oblong, and 12–20 cm (5–8 inches) long. In the autumn the leaves turn a brilliant red. The pendulous fragrant white flowers, about 1 cm (0.4 inch) long, grow in clusters 20–25 cm (8–10 inches) in length; the flowers are replaced by erect whitish capsular fruits, which make a pleasant contrast with the leaves.