The WALA Plant Library

Synonyms for Olive: none
Scientific Name: Olea europaea L.
Family: Oleaceae (olive family)


Olive groves epitomise the Mediterranean region. Hot summers, with shimmering air and the chirping of hundreds of cicadas, and the dry groves with their gnarled, often bizarrely shaped trees, some of them hundreds of years old, really belong together. The oldest known olive tree in Europe, which grows in Montenegro, near the town of Bar, is estimated to be more than 2000 years old.
It takes decades for these trees to reach their final height of up to 20 metres. The evergreen trees found in olive groves are usually much, much smaller. They are pruned regularly to make the olive harvest easier. The bark, which is green and smooth in young trees, becomes rough and cracked as the trees get older. The white or yellow flowers, which blossom from the end of April to the beginning of June, grow in clusters of up to forty florets. The wind-pollinated flowers develop into drupes, the olives themselves, which are initially green but turn black or brownish-violet once ripe. The tree often does not yield fruit until it is seven years old and bears a substantial yield only every two years, a phenomenon known as alternation. Harvesting starts in October and can go on into March.
Olive trees are ideally suited to their dry native habitat. Their roots can reach a length of six metres and draw up water from deep underground. The undersides of the narrow leathery leaves are covered with little hairs (stellate pubescence) which protect them against evaporation. The undersides of the leaves are also covered with slits openings into the inside of the leaf through which the plant takes in carbon dioxide but can also lose fluid. The stellate hairs catch escaping fluid at the opening of the slits and return it to the leaf.