Taxonomy - Olea is a genus of about 20 species in the family Oleaceae, native to warm temperate and tropical regions of southern Europe, Africa, southern Asia and Australasia. They are evergreen trees and shrubs, with small, opposite, entire leaves. The fruit is called a drupe. There are literally hundreds of cultivars of olive tree. Much like apples, trees with different fruit characteristics have been developed over hundreds of years. The species is very variable and no two trees ever seem to be quite the same. As far as bonsai is concerned we are going to encounter three main groups where the foliage is the defining characteristic.
Olea oleaster, a wild olive whose cultivar "Olivastro" is used as rootstock for O. europaea; formerly classified as the subspecies O. europaea oleaster. By far the best type for bonsai cultivation. Tiny leaves, vertical growing twigs when mature. Good examples will have spectacular bark and natural deadwood. Generally collected from the wild in costal regions. Unusually for a dwarf foliage type oleaster is extremely vigorous and forgiving. Most expensive but this is the one to buy!
Olea sylvestris, a small-fruited wild olive of the Mediterranean region. Medium size dark green shiny leaves generally more rounded than oleaster. Looser growing habit. More susceptible to fungal problems in very damp conditions than oleaster. Slower growing than oleaster but with care can produce a very impressive bonsai tree.
Olea europaea, the primary type of olive cultivated for fruit production. Most come from old olive groves. Large oblong grey leaves, very loose habit. Tolerant of most conditions. Good quality bark is rare with this type. Big cheap trees are often available in general nurseries and garden centres. In the UK this type is very poor, generally showing weak growth and susceptible to fungal probelms like peacock spot and pest infestation particularly scale insect. Very hard to produce dense foliage masses without very strong sustained sunshine. Best avoided for bonsai use in the UK.
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HEART OF THE MEDITERRANEAN - THE OLIVE TREE Prior to cheap airfares very few of us in Blighty would have been capable of identifying an olive tree. Today most folk with even a small interest in arboricultural matters will recount tales of being impressed by the ancient olive trees of some exotic...
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