white alder, deciduous shrub or small tree (Clethra alnifolia) native to the Appalachians, named for the resemblance of its leaves to those of the unrelated true alders. It is cultivated as an ornamental for the fragrant white or pinkish blossoms. Similar in appearance and also cultivated are the sweet pepper bush, or summer sweet (C. acuminata), of a somewhat wider range, and a Japanese species (C. barbinersis), whose young leaves are eaten with rice by peasants in its native localities. Most other Clethra species are of tropical America. They are good honey plants. White alder is classified in the division Magnoliophyta, class Magnoliopsida, order Ericales, family Clethraceae.