The olive trees (Olea europaea) are the plants from which olives or olives are obtained, but there are many other species of the genus Olea, all very similar, but with unique characteristics. This genus is composed of 33 species They can be found throughout Africa, Mediterranean Europe, tropical Asia, New Guinea, and eastern Australia.
In this article we are going to talk about everything there is to know about these plants, trying to make some less common species known.
Common characteristics of the genus Olea
Image - Wikimedia / David Brühlmeier
All species are trees or shrubs of dense wood, with simple, opposite leaves and with entire margins. The leaves are usually leathery (hard), especially in species with dry climates. The shape of the leaves is oval and tipped, being much more elongated and thinner in dry climates and wider in tropical ones. The flowers are small, with four petals, and appear grouped in cymes. The fruit varies in color, but it is always the same as olives, a drupe with a hard endocarp (the pit) that protects the seed.
As for care, it is not easy to talk about them in general due to the different climates in which they grow. Furthermore, there is no reliable information on species other than Olea europaea, since they are not usually cultivated.
As you know, olives (the fruit of Olea europaea) are used both to extract oil of very good quality to food after subjecting them to a certain process. This species is also used for firewood, especially when they no longer give large productions or by pruning them. It is also very common to use older specimens as ornamental plant, sometimes pruned in curious ways. Its wild variety, the wild olive tree, can also be used to extract superior quality oil (although each fruit produces much less), but the most common is to cultivate it for bonsai or use it in reforestation. Wild olive is also often used as an olive tree graft base.
They are also given other uses to olive trees, using the oil as a base to make perfumes or soaps and other cosmetic products, or even by cooking leaves or bark and using it as a medicinal product. The rest of the species may be used in their places of origin, but not outside of there. There were some other species that could be seen in botanical gardens, such as African wave, but the vast majority are now considered subspecies of Olea europaea. The only one who can receive wood use es Olea capensis, an African tree with one of the hardest woods (it is called ironwood).
Most outstanding species
Olea europaea
Very variable species, which can range from arboreal to little more than a bush. It is by far lthe most economically important species of the genus Olea, one of the main Mediterranean crops. It is usually called Olea europaea only cultivated olive trees, with thick trunks, lanceolate, curved leaves and a silver underside. Generally black fruit, large in size compared to the rest of Olea, although it depends on the variety. Smooth bark, but very bulky trunk with age. Actually this name also includes all the subspecies that we are going to see below. The correct name for cultivated olive trees is Olea europaea subsp. europaea var. europe. Or for short, Olea europaea followed by the cultivar name.
As for the care, which is the same for all subspecies: They prefer to be in full sun, although they tolerate some shade. They withstand drought very well, although they grow better with a regular supply of water. They are not at all demanding with the type of soil, as long as it has good drainage. They withstand frost well, but here the subspecies and cultivar do matter, some withstanding temperatures below -10ºC and others having a hard time below -2ºC.
Olea europaea var. sylvestris
El wild olive. Native to the entire Mediterranean region. Actually this scientific name is not entirely correct, since it is not complete. To refer to him, the most correct thing is to call them Olea europaea subsp. europaea var. sylvestris. Shrubby in appearance, generally smaller than olive trees, with much finer trunk and branches. Its leaves are small, oval, flat, with a shiny dark green upper surface and a light green underside. They often produce fine twigs transformed into thorns.
In Mallorca we find the ullastre, which is a variety of wild olive with smaller size and more rounded and smaller leaves.
Olea europaea subsp. cuspidate
Formerly called African wave. It is practically the same as cultivated olive trees, but with smaller fruit and an orange instead of silver underside. It also generally has a larger size. Its bark starts out smooth, but eventually breaks into tiny plates. Have a large distribution area, occupying the entire southeast of Africa, passing through the Arabian Peninsula to parts of southern Asia.
Olea europaea subsp. guanchira
Endemism from the canary islands. Otherwise, almost indistinguishable from wild olive, although without thorns.
Olea capensis
The iron olive tree, with the thickest and hardest wood of the family, so much so that it sinks. The leaves are lanceolate, large, more similar to those of the laurel than to those of the olive trees, of the same light green color on the upper side and lower side. It becomes a large tree, up to 40m, with a very striking bark, in vertical white sheets on a black background. The fruit is black and very small, even smaller than that of the wild olive. Its main distribution is Tropical africa, but it is also found in South Africa and Madagascar.
Other species
There are 30 other species of Olea, but they are very little known and there is practically no information about them. The most remarkable thing is that many of them have very shiny leaves, similar to those of some ficus (such as Olea paniculata, which looks like a Ficus benjamina) or privets. In fact, many species of Olea before they were considered ligustrum.
What do you think? Did you know that there were more species of Olea plus Olea europaea? The pity is not being able to recommend them, since not even seeds are sold.
