buckwheat tree, (Cliftonia monophylla), evergreen shrub or small tree of the family Cyrillaceae, native to southern North America. It grows to about 15 m (50 feet) tall and has oblong or lance-shaped leaves about 4–5 cm (1.5–2 inches) long. Its fragrant white or pinkish flowers, about 1 cm across, are much visited by bees.