Bougainvillea, (genus Bougainvillea), genus of about 18 species of shrubs, vines, or small trees, belonging to the four-o’clock family (Nyctaginaceae), native to South America. Cork tree, (genus Phellodendron), genus of several eastern Asian trees in the rue family (Rutaceae) usually having corklike bark. ging to the four-o’clock family (Nyctaginaceae), native to South America.