Commonly called sourwood, sorrel tree, or lily-of-the-valley tree, most people in the biz refer to Oxydendrum arboreum by its genus name. The oxydendrum is a medium size tree, known for its red to reddish-purple autumn color.
This plant prefers acidic, peaty, moist, well-drained soils in full sun to part shade. It is tolerant of shade and dry soils and moderately tolerant of salt. It is intolerant of pollution and urban areas. It has a slow growth rate and no serious pest or disease problems. It makes an excellent specimen or understory tree or planted in small groups in a woodland garden.
In mid-summer, small, white, urn-shaped flowers mature on panicles. By the fall, those flowers have set seeds, which very closely resemble the original flowers.
And those flowers closely resemble those of mountain andromeda, another member of the Ericaceae family. Members of this family — including azaleas, rhododendron, and blueberries — prefer acid soil.
Fun fact: Honey made from the nectar of these flowers is highly prized for its color and flavor.
Also: This plant has a low flammability rating. Good to know.