winterberry, name for two species of shrubs or small trees of the genus Ilex of the family Aquifoliaceae (holly family), native to the eastern half of North America. Both are deciduous but have winter-persistent bright red or yellow berries. The Virginia winterberry, or black alder (I. verticillata), has toothed but spineless narrow leaves, hairy beneath. The similar smooth winterberry (I. laevigata) has smooth leaves. Winterberry is classified in the division Magnoliophyta, class Magnoliopsida, order Celastrales, family Aquifoliaceae.