oleaster, common name for members of the Elaeagnaceae, a family principally of shrubs with leathery leaves and a dense covering of glistening hairs. Most members of the family are steppe and rock plants of the Northern Hemisphere; a few species are indigenous to the United States. Several are cultivated as hardy ornamental shrubs, especially the buffalo berry (Shepherdia argentea), whose edible fruits were gathered by Native Americans and by the Alaskan Eskimos; the common oleasters (Elaeagnus angustifolia and related species); and the sea buckthorn (Hippophaë rhamnoides), a native of the Old World. Oleaster is classified in the division Magnoliophyta, class Magnoliopsida, order Proteales.