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.
Propagation
The olive is propagated by means of seeds, cuttings, grafting, and budding. Propagation by seeds is seldom done in this country, as it is so much slower and more troublesome than by cuttings, aside from the fact that the desired variety may not result. The pulp has to be removed, which is done usually by allowing the fruit to rot or by softening with an alkali. Unless removed from the stone, the seed may not develop for two years, otherwise the seed usually sprouts the first year.
Propagation by cuttings is the commonest and easiest method, as the cuttings root readily, and either old or new wood may be used so that the cuttings may be large or small. Cuttings sent from Europe are usually in the form of truncheons, and these may be cut into pieces like firewood and will root.
The story is told of a grove in Morocco in which the trees exhibited a peculiar arrangement. The reason given for this was that a king and his army on the way to the Sudan had encamped for the night, and stakes or pickets to tie the horses had been cut from a grove near by. The pickets were left and had developed into trees. This seems probable enough when it is considered that pieces of branches are taken, one end whittled to a sharp point and driven into the ground, and that these pieces will take root and develop. An olive company in California has recently transferred 3000 trees, 26 years old, from San Joaquin County to Oroville and Marysville. The trunks were sawed off about 18 inches above the ground, and the roots 12 inches from the stump. In a planting made 6 years previously the same method was used and resulted successfully.
Where trees are found undesirable for some reason, resort is had to budding or grafting. By these means the undesirable trees are not a complete loss, and results are obtained sooner. Many times varieties are obtained from Europe which on developing are not found suited to the conditions in this country; these plants may be used as stock for desirable varieties or some desirable variety is obtained which may be propagated rapidly by these means.
The pruning must be done by persons of understanding, as the fruit is borne only on the two-year portion of the branches, and provision must be made to cut excessive growth in the season of too heavy development and stimulate in the season of poor development. The pruning thus regulates the growth of the branches which two years later will control the production of the fruit.
Pruning of very large branches is sometimes done to admit more light and heat to the darker, cooler parts of the tree. The small branches thus provided in turn furnish nursery stock. Pruning is done in late winter and early spring. From March to October no pruning is done, but the trees are carefully tended through cultivation, irrigation, and fertilization.
In California the young stock is set out in the groves in April, and about 35 feet apart. During the non-bearing period, the land between, which like all California groves, is kept in good cultivation and free from weeds, is utilized frequently for other crops.
Though numerous stories are written of the remarkable ability of the olive tree to grow and bear in exposed situations, and with only small amounts of soil and water, the olive, like all other fruit trees, requires both cultivation and an adequate amount of water if a constant and abundant harvest be desired. As the groves are irrigated, the proper amount of water may be supplied at all times. The water is conducted through a system of underground pipes, which are provided with outlets at the end of each row of trees. From these outlets the water is directed into furrows to water the trees. As the irrigation is conducted by underground pipes, the groves are easily cultivated.
Products
It would seem that the olive is rightly and appropriately called the “Tree of Abundance,” for all parts of it have been used, and to the ancients, even with their limited cuisine as compared with that of today, it was a symbol of plenty, witness the apostrophe of King Sennacherib, made centuries before the Christian era, who called Assyria “A land of corn and wine; a land of bread and vineyards; a land of oil, olives, and honey.”
FLOWERS
In ancient medicine the blossoms of the olive were highly esteemed, but are not mentioned in the medicine of today. They were used as poultices to alleviate pain, sometimes alone, sometimes mixed with other substances.
LEAVES
The leaves were also used in medicine, a decoction made from them being said to stop bleeding, and on account of their astringency to reduce inflammation. The leaves and bark have an acrid and bitter taste, and have been prescribed as substitutes for cinchona. In France an extract of the leaves is used as a febrifuge, and has also been found valuable in preventing hectic paroxysms.
From time immemorial the leaf and branch have been employed as a symbol of peace, and have appeared in sculpture and painting. No more beautiful emblem than the olive branch can be selected or devised to symbolize both peace and victory, and as such has been known through all the ages. Egyptian mummies, dating from the 20th to the 26th dynasty, have been found surrounded by garlands of olive leaves, and the tomb of the hero of today will oftentimes have its sculptured olive branch, telling its story and making its appeal stronger than could be made by words.
Besides serving for esthetic purposes, the leaves, in spite of their astringency, are eaten by animals as forage, so that the trees have to be protected from them. It is curious that with all the ravages made by animals on the olive trees in the neglected mission gardens in California, after the missionaries had gone, some of these same trees furnished scions for many of the olive groves of today.
WOOD
The wood of the olive tree is much prized for certain purposes. It is very close, fine-grained, yellow to yellowish brown with irregular wavy brown to black lines and mottlings, especially near the root. It has no distinguishable annual rings or pith rays, and has evenly distributed vessels. It takes a beautiful polish. At present it is employed chiefly in lathe-work and carving for small fancy articles, and for cabinet work.
In ancient times it seems to have had a much wider application, due no doubt to the size of the trees, which were larger as a result of not being subjected to the rigorous cultivation and pruning which they receive today. The Bible states that olive wood was used in the Temple. In the time of Pliny it furnished material for construction of ships, for wagon spokes, wedges, columns, pedestals, statues, and furniture. The Romans used both the wild and cultivated trees. The wood industry was developed in the vicinity of Nice in both France and Italy, and still flourishes. A considerable amount has been exported to England in recent years for the manufacture of walking sticks. The poorer quality is used for firewood, is inflammable, and produces great heat.
BARK
The bark contains a large amount of tannin. For medicinal purposes it is reduced to powder and acts as an astringent, a tonic, and a febrifuge. In warm climates a resin is exuded from it which solidifies in the air. It is called Lecca gum, as it was first found near Lecca. It contains some benzoic acid among other constituents and in ancient times was prescribed in medicine, but is not at present, and the gum is considered valueless.
FRUIT
The fruit has been considered a choice food at all times. It has appeared at the feasts of epicures, both ancient and modern, as a relish, and to be eaten at the end of the repast as part of the dessert, and at all times it has also furnished a staple food for the poor in the Orient and in Greek and Latin countries. Those who were well provided were admonished to have care for those less fortunate: “When thou beatest thine olive tree, thou shalt not go over the boughs again; it shall be for the stranger, for the fatherless, and for the widow.” (Deuteronomy XXIV., 20.) The people obliged to live frugally have found it a great resource, particularly in Lent and for those at a distance from the sea unable to obtain fresh fish. It is said that Plato preferred olives to all other foods, and often made a meal on them alone.
Though olives are known and consumed throughout the civilized world, comparatively few persons, aside from those living in the regions of their cultivation, know that olives have to undergo certain treatment before they can be eaten. It is a common practise in olive regions to encourage the visitor to taste the fruit directly from the tree. The fruit, both green and black, looks so fine and tempting, that the disgust on tasting is correspondingly great. It is claimed that some of the older varieties could be eaten without preparation, that they dried naturally, and were sweet like raisins.
The olive contains a bitter and acrid substance or substances which must be removed before the olives are edible. It is referred to in most of the literature as a “bitter principle”, and has been called an acid, a tannin, and more recently a glucoside. Cruess has repeated the work of the various investigators, who claimed these different substances, and as a result has come to the conclusion that it is a glucoside, that is, a combination of glucose with another compound.
In immature fleshy fruits there is usually an accumulation of acids, tannins, and sometimes starch. As ripening proceeds, carbohydrates and aromatic substances are formed, and the bitter, acrid, or astringent taste disappears. In the olive there is no starch found at any stage of maturity. Glucose has been found in all stages, and is supposed to be the substance from which the oil is formed. The oil is in very minute quantities in the fruit up to the time when the pit is formed, from then on it increases gradually up to its maximum when the fruit is not quite mature. In the plant economy the fat or oil is one of the most important food reserves of plants. All parts of the fruit – rind, flesh, stone, and seed – contain oil, the fleshy part, forming about 80 % of the fruit, containing the largest amount.
Contrary to the condition existing in most fruits, the bitterness remains through all stages of development in the olive. A substance of glucosidic nature, given the name “oleuropeine”, has been isolated, and found to be of extreme bitterness. This may be the substance or one of the substances which cause the inedibility of the untreated olive.
The oil is the most important constituent of the fruit on account of its high food value and its use in the industries. It is used to a large extent in cold countries and also in dry countries where there are few cattle, the oil taking in the various culinary operations, the place of butter and other fats.