This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Shrubs or trees, mostly silvery-scaly, or stellate-pubescent, with entire alternate or opposite leaves, and perfect polygamous or dioecious flowers clustered in the axils or at the nodes of twigs of the preceding season, rarely solitary. Lower part of the perianth of perfect or pistillate flowers tubular or urn-shaped, enclosing the ovary and persistent, the upper part 4-lobed or 4-cleft, deciduous (obscurely 2-lobed in the Old World Hippophaë); perianth of staminate flowers 4-parted (2-parted in Hippophaë). Corolla none Stamens 4 or 8, those of perfect flowers borne on the throat of the perianth; filaments mostly short; anthers 2-celled, the sacs longitudinally dehiscent. Disk annular, or lobed. Ovary sessile, 1-celled; ovule 1, erect, anatropous; style slender. Fruit drupe-like, the perianth-base becoming thickened and enclosing the achene or nut Seed erect; embryo straight: endosperm little or wanting.
Three known genera and about 20 species, widely distributed.
Stamens as many as the perianth-parts; flowers perfect or polygamous; leaves alternate.
Stamens twice as many as the perianth-parts; flowers dioecious; leaves opposite.