Varieties
The wild olive Oleaster is said to have been the original form, called by Linnaeus Olea europaea sylvestris, later by De Candolle Olea europaea oleaster and the cultivated form Olea europaea sativa. The reason for this belief is said to be the oleaster seeds reproduce trees true to type, whereas the seeds of sativa produce trees having the characteristics of oleaster but, though oleaster under cultivation becomes modified in various ways, it does not produce fruit like sativa. Whichever form was the original, the subjection to cultivation for over 4,000 years, under the varying conditions of soil, climate, and methods of cultivation, has produced many varieties. Many of these doubtless are the result of accidental modifications, more or less fixed by successive cultivations. At the present time there are certain well-defined varieties which are cultivated, and of which the characteristics are well known, so that varieties may be selected according to the purpose desired, whether for the preservation of the fruit green, half ripe, or ripe, or for extraction of oil.
Of the large number of varieties introduced into California, Wickson reports analyses made by the State university on 57 varieties. Of these only a comparatively few were retained as worthy of cultivation, chief among these being the Mission olive, the one planted originally in California in the old mission gardens. Wickson states there are several sub-varieties of this form.