the olive tree & its fruit
The olive is an evergreen tree growing to c. 15 metres in height, with a spread of c. 10 metres. The tree can be kept to about 6 metres with regular pruning. They are long lived with a life expectancy of 500 years. They are also extremely tenacious and will easily resprout even when chopped to the ground. They can be very distinctive and attractive trees due to their graceful, billowing appearance, greyish foliage and gnarled trunks and branches.
The olives feather shaped leaves grow opposite one another. Their skin is rich in tannin, giving the mature leaf its grey-green appearance. The leaves are replaced every two or three years , with leaf fall usually occuring at the same time new growth appears in the spring.
The olive tree needs a long, hot growing season to properly ripen its fruit, no late spring frosts to kill the blossoms and sufficient winter chill to ensure fruit set. Although trees can withstand temperatures as low as 12 degrees Fahrenheit, unripe, green fruit is damaged at about 28 degrees but ripe fruit will withstand somewhat lower temperatures. Hot, dry winds may be harmful during the period when the flowers are open and the young fruits are setting. However as mentioned elsewhere, the olive tree has an almost titanic resistance and will survive and fruit well even with considerable neglect.
The olive's small, fragrant, cream coloured flowers are largely hidden by its evergreen leaves and grow on a long stem arising from the leaf axils. The olive produces two kinds of flowers: a perfect flower containing both male and female parts, and a staminate flower with stamens only. The flowers are largely wind pollinated with most olive varieties being self-pollinating, although fruit set is usually improved by cross pollination with other varieties.
The olive fruit is a green dupe, becoming generally blackish-purple when fully ripe. A few varieties are green when ripe and some turn a shade of copper brown. The cultivars vary considerably in size, shape, oil-content and flavour. The shape ranges from almost round to oval or elongated with pointed ends. Raw olives contain an alkaloid that makes them bitter and unpalatable. Only a very few varieties are sweet enough to be eaten after sun drying. The trees reach bearing age in about 4 years.
Regular pruning both regulates production and shapes the tree for easier harvest. The trees can withstand radical pruning, making it easy to keep them at a desired height.The olive never bears fruit in the same place twice and usually bears on the previous years growth.
The olive tree is affected by some pests and diseases, although it has fewer problems than most fruit trees. Around the Mediterranean the major pests are medfly and the olive fruit fly, Dacus oleae.
If olives are to be eaten rather than pressed to make oil, they need to be cured. A common curing method is the lye-cure process in which green or near-ripe olives are soaked in a series of lye solutions for a period of time to remove the bitter principle and then transferred to water and finally a mild saline solution. Other processing methods include water curing, salt curing and Greek-style curing.