The wild olive is a rather straggling small tree or bush with thorny branches. The cultivated varieties are more compact and less spiny with smooth leathery evergreen leaves, grayish-green above and whitish below. Old trees seldom exceed 30 feet in height, but the gnarled knotty trunk may be over twenty feet in circumference. The very hard wood with its beautiful grain and color is prized by cabinetmakers. The olive is a stone fruit with the appearance of a purple plum when mature The oil, contained in the flesh, may make up as much as 60 percent of the weight of the fully ripe fruit.
Speed is essential because the oil in bruised fruit quickly becomes rancid.
Lower grades of oil are greenish in color and are used for cooking, in medicine, or for making Castile soap. A total of about one million tons of olive oil is produced in the world each year. Of this, Spain furnishes over 40 percent, followed by Italy, Greece and Portugal. Afresh olive picked off the tree, no matter how ripe, has a vile intensely bitter taste. In making pickled olives, either green or ripe, this flavor is removed by soaking them in weak lye.