Clethraceae  The Clethraceae are a small family of flowering plants in the order Ericales, composed of two genera, "Clethra" and "Purdiaea", with approximately 75 species. They are native to warm temperate to tropical regions of Asia and the Americas, with one species also on Madeira. In the past, most botanists included only "Clethra" in the family, but recent research has shown "Purdiaea", previously placed in the closely related family Cyrillaceae, is more closely allied to "Clethra".