This section is from the book "Sub-Alpine Plants Or Flowers Of The Swiss Woods And Meadows", by H. Stuart Thompson. Also available from Amazon: Sub-Alpine Plants: Or, Flowers of the Swiss Woods and Meadows.
Name taken from Olea the Olive. Flowers regular, generally small. Calyx with 4-5 divisions or sometimes o. Stamens 2. Leaves simple or pinnate, always opposite. Fruit a berry or samara. A family of trees and shrubs inhabiting the temperate and hot regions of the two worlds; but comprising no Alpine species.
Flowers dioecious. Fruit a broadly-winged samara. Leaves with 9-15 opposite leaflets, appearing after the flowers.
This well-known tree is frequently seen at about 3000-3800 feet in Switzerland, but never in large quantities.
Temperate Europe, as far north as Scandinavia, Western Asia.