The olive tree is the oldest known cultivated tree in history. Olives were first cultivated in Africa and then spread to Morocco, Algiers, and Tunisia by the Phoenicians. The olive tree is an evergreen tree with gray-green leaves and small white fragrant flowers that grow in the spring and produce a lot of pollen. A young olive tree has smooth gray bark, but as it gets older, it gets very gnarled. A mature tree can reach a height of 25 to 30 feet, and live for hundreds of years. Some have even lived to be a thousand years old. To be able to survive in a hot and dry climate, olive trees have small leaves with a protective coating and hairy undersides that slow transpiration. An olive tree tends to grow dense, thin branches. To produce more fruit, the tree is pruned heavily. Olives ripen through the autumn and into the winter. As the oil content increases, the olives change color from green to violet to nearly black. The green olives are harvested first. Olives can be hand picked, gathered with a special wooden rake-like tool, or brought down by hitting the branches with long poles. A net is laid down on the ground to catch the harvest.
Olive - Olea europaea - Blue Planet Biomes, http://www.blueplanetbiomes.org/olive_tree.htm (accessed January 24, 2017).