The olive is one of the core agricultural products of the Mediterranean diet, along with grain and the grape. The tree, its fruit and the oil derived from it have achieved iconic status in Western and Middle Eastern culture. The plant is a tough, resilient producer that can thrive under difficult conditions.
The olive tree is native to the eastern Mediterranean. It has since spread around the world. However, the main olive-producing region is the classic world of the Mediterranean and Mesopotamia, embracing the entire Mediterranean basin, those parts of North Africa and Southern Europe that face the Atlantic (Morocco and Portugal), and as far east as northern Iran.
These trees tend to be short and stocky. While only the rarest olive tree ever reaches a height over 40 feet, it is easy to find gnarled old olive trees with trunks that are 10 feet in diameter. They are evergreen, with very hard wood, and have an extensive root system that allows them to endure droughts and arid conditions well. The trees are extremely hardy. A properly cared-for olive tree can be productive for several hundred years. They endure cold well, but temperatures below 14 degrees Fahrenheit will damage them.
Olive trees prefer coastal areas and calcareous soils. Given their ability to thrive under dry conditions and in rocky, limestone-encrusted areas, this makes the plant an ideal candidate for planting in rocky Mediterranean soil that wouldn't support much else.
The olive is almost inedible as a ripe fruit, and some varieties are marginally poisonous. To make them edible, they are typically either fermented or cured. Olives are harvested throughout the autumn, with some varieties not reaching their peak until mid-winter.
Olive oil is extracted by grinding the fruit into a paste. The oil is removed mostly by use of a centrifuge and then filtration. Some factories go on to get the last bit of oil out of the paste by using chemical solvents.
Olive trees are vulnerable to a few specific pests. Rabbits tend to eat the bark, which has the potential to damage and even kill the trees if allowed to go too far. The curcillo beetle gnaws on the leaves, and the black scale bug can infest the trunk and damage fruit production. Finally, there is a species of fly that directly attacks the olives.