Oxydendrum arboreum aka Sourwood

Oxydendrum arboreum, or sourwood, is a tree in the blueberry family. It sheds its leaves each year and grows slowly. Its home range spans the eastern and southern United States. It runs from Pennsylvania to northern Florida, west to Ohio and Louisiana. Wild trees grow near streams on ground that drains well. Garden trees often reach 20–30 feet [6–9.1 metres] tall. They spread about 10–15 feet [3–4.6 metres]. RHS gives larger sizes, reaching 39 feet [12 metres] tall. Its stated spread reaches 26 feet [8 metres]. Wild trees can reach 100 feet [30.5 metres].

The crown forms a pyramid, with branches that dip then rise. Young twigs have smooth red or green bark. Older bark turns gray-brown and splits into rough blocks. The glossy green leaves grow one at each stem joint. They have pointed tips and fine teeth along their edges. Their sour taste gives the tree its common name. Fall leaves turn red, purple, or sometimes yellow. The color can last well into late fall.

Small white flowers hang in long clusters at branch tips. Each flower has an urn shape and a light scent. Sources place bloom from May through August, often June or July. Bees and butterflies visit the flowers for nectar. Bees use that nectar to make sourwood honey. Dry seed capsules follow the blooms and ripen in fall. They turn brown or silver-gray and stay after leaf drop. Tree hollows give shelter to bats and other small animals.

Grow sourwood in moist, acid soil that drains well. It favors soil rich in organic matter and needs summer moisture. It grows in sun or part shade. More sun brings more flowers and stronger fall color. Choose a sheltered site away from polluted urban areas. Move trees while young, since older ones resist transplanting. Sources list USDA zones 5–9 and UK hardiness H6. Severe winters can kill twigs, especially on young or moved trees.

Sourwood suits patios, woodland edges, and small groups of trees. It offers flowers, fall color, and winter seed clusters. Grass can compete with it, making lawns a less suitable site. Few pests or diseases cause major trouble. Fall webworm, leaf spot, and twig blight can occur. PFAF lists raw leaves as edible and reports no known hazards. The leaves contain oxalic acid, so that is not proof of complete safety. Leaf tea and chewed bark have recorded folk medicinal uses. Its hard wood has served for handles and paneling.