The Phyto-Philes: Wild Olive
Created | Updated Apr 6, 2014
African Wild Olive
Willem says: 'The Phyto-Philes are for plant lovers of every size and shape, colour and flavour. As with my Colours of Wildlife column, I'll be featuring one species per article, illustrated with sketches, paintings, and/or photos. Over time I hope to be showcasing the amazing diversity of weird and wonderful plants that occur in South Africa, while also from time to time looking at the flora of other countries. While featuring many spectacular species, I'll not be neglecting the smaller, more humble kinds that are nevertheless fascinating in their own right.'
The African Wild Olive is a close relative of the commercially grown olive tree, Olea europaea. Indeed, it is considered part of the same species, only given a separate subspecies: Olea europaea subsp. africana. Wild olive trees grow over most of Africa in a wide variety of habitats, from dry scrub to forests, and also on the Mascarene Islands (east of Madagascar), the Arabian Penninsula, and the warmer parts of Asia as far as China. In South Africa they grow over almost the entire country, except for the driest parts of the Karoo and the Kalahari Desert. Several other members of the olive family grow in South Africa, ranging from the tall Ironwood trees down to small herbs.
This is a tree I know very well! I have a specimen in my garden and I see them frequently in the veldt. They are among the few tree species that grow in the high grasslands of the Free State where I've spent much time on my uncle Kerneels' farm. When I was studying at the University of Pretoria, I was in the hostel called ‘Olienhout’, which is the Afrikaans name for this tree. Wild olive trees are quite abundant in and around Pretoria. The photos you see here were taken in the Pretoria National Botanic Gardens. They show ancient specimens that certainly pre-date the establishment of the gardens … perhaps a century or more in age. They are gnarly and rather low-growing but with very wide spreading crowns that reach right to the ground. The branches are very sturdy, hardly bending at all under my weight! Wild olive trees are fairly easy to identify, with their dense crowns of rather small, narrow leaves that are dark above and lighter olive green below.
Hard and Heavy Wood
Olive trees have some of the hardest and heaviest of woods. It is one of a few kinds of wood that sink in water, having an air-dry density of 1140 kg per cubic meter (1800 pounds per cubic yard). In addition to its strength, the wood is termite- and borer-resistant, has a fine grain, and is fragrant. It is a golden or reddish brown, which darkens with age, and easy to work to a very smooth finish. Consequently it is highly sought after for furniture, wood carvings and ornaments. But in nature, most specimens are gnarly with crooked trunks and branches! Indeed this probably saved most of them, many of the tall, straight specimens having been cut down. Somewhat less straight specimens can still be used for sturdy fence posts. But there are still a great many fine wild olive trees left out there. The current champion specimen on record grows in the region of Potgietersrus/Makopane (a town close to my hometown of Polokwane) and measures 14 m/47' in height, with a trunk 1.6 m/5.3' in diameter. In forests and ravines the trees are slender but taller, reaching as much as 18 m/60'.
A Most Valuable Tree
Wild olive trees are amazingly valuable, ecologically. First there’s the fruit! Wild olive trees have fruit that are much smaller than those of the commercial olives. They reach only about 1.2 cm/0.5" in length. They turn from green through red to black as they ripen, as you can see in my drawing. The fruit are generally not quite as tasty as commercial olives, often being rather bitter, but some taste good enough. Above all they are nutritious, and lots of birds (such as the Rameron Pigeon) and animals eat them. Monkeys and baboons pick them off the trees, while wild pigs and warthogs eat the fallen fruit. The dark juice of the fruit can be used for ink!
But the leaves of these trees are as valuable as the fruit. They are browsed by many antelope species. They are also browsed by cattle, sheep and goats. In some dry regions, wild olive trees are browsed down to the point where they grow as nothing more than low shrubs. This stimulates the continuous growth of new leaves. The browsers prefer young leaves, since the older leaves become tough and bitter. Humans too can use the young leaves for making a refreshing tea.
Humans have several more uses for wild olives. The wild trees are hardier than cultivated olive trees, and are resistant to many of the diseases that plague them. Therefore wild olive trees can be used as stock for grafting commercial olive trees. The trees are evergreen and very hardy, being able to handle extended droughts as well as considerable frosts. They have extensive root systems and can help stabilize the soil in regions prone to erosion. Trees can also be planted as windbreaks and for shade. They respond well to pruning and can be trained to be much neater in shape when growing in the garden than they usually are in the wild. They can also be shaped into delightful bonsai tree specimens! But best results come from considering their craggy natural aesthetics.
There are a few medicinal uses recorded for this tree. An infusion of the bark is used against colic; an infusion of the leaves is used as a gargle for sore throats and as an eye lotion for humans as well as animals. Both the leaves and the bark are used to treat fever.
Growing Wild Olives
Extract the seeds from fresh fruit. Plant them in well-draining potting soil in nursery bags at the start of spring, at a depth of about half an inch. Keep moist and warm. The seedlings rapidly form long taproots so be careful not to damage these when replanting. In a favourable climate such as my home town of Polokwane – warm summer, not-too-cold winter, moderate rain in spring and summer and dry autumn and winter – the trees grow well. They can be boosted by giving them just a bit of extra water in the winter for their first year or two of life. They can put on 0.8m/32" of height per year for several years, becoming a nice little tree by the age of five. In harsher climates they grow slower, sometimes very slowly, but they remain healthy and can live for very long. Pruning the young tree can not only improve its shape, but also stimulate vigorous new growth. In the garden, they typically reach a height of 3m/10' to 7m/23'. An interesting quality they have is bark with just the right kind of PH to grow epiphytic orchids on!
