This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Shrubs, trees, or herbs. Leaves simple, alternate or opposite, deciduous or evergreen, exstipulate. Flowers usually small and inconspicuous, in terminal cymes or panicles, or amentaceous or capitate with a coloured involucre. Calyx-tube adherent to the ovary. Petals none, or 4 or 5, rarely more. Stamens 4 or 5. Fruit drupaceous, 1- to 4-celled, or with 1 to 4 1-seeded stones. A small order of about seventy-five species, widely scattered throughout the world, but most abundant in the temperate regions of the north.