Olea L. (1753), in the family Oleaceae, contains around 20 species in southern Europe, Africa, and Asia.

Description Trees to 15m, or shrubs, sometimes spiny. The leaves are opposite, evergreen, elliptic, rarely toothed, often with silvery scales. The flowers are small and white or greenish, unisexual or bisexual, in clusters. Sepals 4, joined at the base. Petals 4, joined at the base into a short tube. Stamens 2, inserted in the tube. Ovary superior. Pollination is by insects. The fruits are greenish-purple, fleshy berries with 1 large seed.

Key Recognition Features The greyish, narrow, opposite, evergreen leaves and the small, green flowers followed by blue or yellow fruit.

Evolution and Relationships The affinities of Oleaceae are traditionally with Buddlejaceae, Scrophulariaceae, and Plantaginaceae: recent DNA studies support this. Olea itself is close to Chionanthus and Osmanthus both of which also have fleshy fruit.

Ecology and Geography On dry hillsides and in forest; from the Mediterranean region to South Africa and across Asia to Australia and New Zealand.

Comment The olive, O. europea L. is one of the most valuable of all trees for its oil and edible fruit. Seed-raised plants are usually inedible, but several cultivars are grown. Cultivated olives probably originated in Arabia or India, and there is evidence of olive cultivation dating from around 3600 bc in the eastern Mediterranean.

Olea europaea Olive
The cultivated olive is native of the Mediterranean region and remains one of the most familiar trees in that landscape, with its gnarled trunk and silvery, narrowly elliptic leaves. Pale green flowers in spring are followed by edible, egg-shaped fruits, which are black-purple when ripe.
Cultivation Though long-lived, olives are not slow growing if given fertile soil and water in summer. Old trees may need their branches thinned to produce a good crop.
Height to 9m (30ft); spread to 6m (20ft). USZ 9–11, surviving -6.5°C (20°F) of overnight frost. Tolerant of summer drought. Z8.