Meet the Trees in Namibian road reserves, The Strangler fig

If you have a penchant for detective work, make sure to stop at this lay-bye along the B8 in the Otavi valley between Otavi and Kombat shown on the photo. Enjoy the shade and take note of the shape of the simple smooth leaves, which taper towards the relatively long leaf stalk. Pluck off a leaf and you will see a drop of white sticky sap oozing from the end of the stalk and the place it was attached to. Now take time to inspect the branches of this tree. You may notice that the growth points of fig tree branches are covered with a sharply pointed little cap. Eventually you may find one or two branches that are partly covered with the light grey, smooth bark of the fig tree and partly by rough grey bark splitting into rectangular sections. You have discovered the remains of the Lleadwood tree (Copmbretum imberbe) which was strangled by the Strangler Fig (Ficus thonningii, now Ficus burkei).

In Namibia this tree is known by several names: E. Strangler fig, Common wild fig; G. Würgefeige A. Gewone wildevy, gewone wurgvy; H. Omukuyu; The botanical name Ficus is the Latin word for 'fig', while the species name burkei refers to James Burke, a 19th century botanist and collector. This species used to be called F. thonningii in memory of the Danish botanist Peter Thonning (1775 - 1807), however, its type specimen, i.e. the pressed specimen which was first described and recorded as such, has been lost and the original description was not very detailed. Since most of the specimens in Namibia fit the description of F. burkei, it is now referred to by this name.

The largest concentration of Strangler Figs in Namibia occurs in the mountainous area around Otavi, Grootfontein and Tsumeb and further northwards in the north central regions and along the Okavango River. They are large, mostly evergreen trees whose trunks often appear quite untidy as a result of the various side shoots and aerial roots which eventually fuse. They can reach a height of up to 20 m.
The typical fig fruit actually is a flower whose base has grown to envelop the other floral parts. The fruits in fact are the little pips inside the fig. With a diameter of only 8 - 12mm the fruits of the Strangler Fig are much smaller than the garden fig. Densely downy and red or reddish when ripe, they are edible but not very tasty.
The Strangler Fig can be very variable. It derives its common name in the European languages spoken in Namibia from the fact that the seed frequently germinates in the fork of another tree species. The seedling develops thin dark red aerial roots, which dangle down the tree until they reach the soil and find additional nutrients. During the course of many years they then develop into a network of flattened white ropy structures which eventually fuse to engulf the entire host, strangling it in the process.

It is always exciting to inspect a strangler fig and I would encourage you to do this as often as time permits. Sometimes you might find one trunk with two different kinds of foliage as on the accompanying photo. The light coloured branch on the photo is that of a Strangler Fig with its red aerial roots. The darker branches are those of the host, again a Leadwood tree.

As hosts so far I have identified Leadwood trees (Combretum imberbe), Tamboti (Spyrostachys africana), Marula (Sclerocarya birrea) and Umbrella thorn (Acacia tortilis), while the Namibia Tree Atlas also mentions the Sausage Tree (Kigelia africana) and the Ana Tree (Faidherbia albida). The Strangler Fig is not a parasite because its roots do not enter the vascular system of the host.

In March 2002 I found a Strangler seedling of about 20 cm growing in the fork of a huge Marula tree (Sclerocarya birrea) on a farm in the Otavi district. It was sitting there like a cheeky little brat dangling its red roots. A year later its branches and roots had grown a few centimetres and I was getting worried about the fate of the magnificent Marula tree. When I inspected that tree again in August 2004 the seedling did not look well at all, which may have been due to the fact that it was winter. I am keen to inspect the tree again as soon as possible to see whether it has recovered and how the host is doing.
As mentioned before, the Strangler Fig can be very variable. In a remote valley of the Otavi Mountains I found such a tree growing on top of a dolomite cliff of about 20 m high, from where it sent down thick white roots cascading over along the rock face, forming a second tree about halfway down as well as another tree right at the base of the cliff.
For any tree lover a visit to Roy's Camp about 50 km north of Grootfontein, also along the B8, is a very worthwhile experience. In addition to ingeniously constructed rustic bungalows and delicious meals the camp provides camping under trees, and above all an interesting hiking trail. Most impressive among the trees to be seen there are a couple of tall Tambotis (Spirostachys africana) whose dark rough trunks are slowly being enveloped by the light grey to almost white roots of the strangler fig (Ficus burkei).

Strong ropes and bark cloth can be made of the inner bark if this tree. The bark is also used to treat flu. While the foliage of the Namaqua fig (Ficus cordata), commonly found on hill slopes throughout Namibia, is readily browsed by stock and game, the leaves of the Strangler Fig are said to be poisonous. The juice obtained by stamping the roots is so sticky that it is applied to twigs and to grass to trap birds. It is said to be strong enough to trap guinea fowl. The root has also been used as a cure for snake bite, syphilis, stomach cramps and skin rashes.

The Strangler Fig tree can be propagated by cuttings or truncheons. Due to its size and its very invasive root system it is only suitable for very large gardens and parks. Ask for seedlings and/or advice at the Forestry nurseries in Okahandja and Grootfontein.

Be sure to stop[ at this beautiful Strangler Fig (Ficus burkei = F thonningii) along the B8 in the Otavi Valley between Otavi and Kombat.