white alder
noun
1An alder, especially Alnus rhombifolia, of western North America.
2The South African tree Platylophus trifoliatus (family Cunoniaceae).
3A white-flowering shrub of moist habitats, Clethra alnifolia (family Clethraceae) native to eastern North America; also called sweet pepperbush.
Origin
Mid 18th century; earliest use found in Thomas Short (c1690–1772), physician.