Meet the Trees in Namibian road reserves

The Windhoek or mountain aloe is a tree but it hardly provides any shade at all and will not be found at lay-bys along our roads, however, it is very conspicuous where it occurs and is therefore included in this series. It will be particularly visible at this time of the year because in the central parts of Namibia its red candelabra-like flowers appear from April to May.

Topped by its characteristic rosette of leaves, the straight single trunk of the Windhoek aloe is covered in its shaggy cloak of shrivelled old leaves, and this is what it looks like for most of the year. In the dry season aloe leaves like those of many other succulents take on a reddish tinge. After the first rains the leaves swell and turn grey green. The red-brown to dark-brown teeth along the leaf margins are about 5 mm long and on young plants the leaves often have white speckles. Eventually the many branched, erect spray of red tubular flowers grows out of the centre of the leaf rosette. The flowers are pale red to deep red with the tips turning yellow during the course of time. The flowers are often covered in a waxy layer giving them a silvery sheen. The fruit is a capsule containing many small black winged seeds. The Windhoek aloe flowers at different times in different regions of Namibia - from October to December in the south, from April to May in the central region and even later in the north. The trunk of this aloe does not branch - if you find the occasional plant with two leaf rosettes that is the result of some injury.

As a visitor to Namibia you may get your first glimpse of the mountain aloe in the Botanical Garden, which you will be passing on your right after the third set of traffic lights as you travel from the Airport into the centre of Windhoek. Here the aloes stand guard on the hill slopes like so many sentinels. As the aloe is the emblem of the city of Windhoek it appears on all municipal vehicles as well as on the city's stationery, hence the name Windhoek aloe.
As the other common name implies, this aloe is often found on hill slopes. It usually occurs on stony ground, either singly or in smaller or larger groups e.g. along the B1 about halfway between Otjiwarongo and Otavi or along the C22 to the Waterberg. It is one of five tree aloes found in Namibia. The most common of these is the quiver tree (Aloe dichotoma) whose branches always divide in two and which is found mainly in the southern parts of the country and along the escarpment. The other three tree aloes are confined to a very restricted area along the Orange River in the vicinity of Rosh Pinah and Sendelingsdrif. The mountain aloe is also found elsewhere in southern Africa but its distribution is mainly restricted to Namibia.

The plant is easily destroyed by fire. In dry years baboons climb the plants to eat the flowers, which contain copious amounts of nectar, and often break down the plant in the process. They are also harmed by rock hyraxes that eat the succulent leaves. In general, succulents do not seem to be able to cope too well with extremely wet seasons as were experienced in Namibia during the rainy season 2010/2011 in particular and to a certain extent in the current season. Quite a number of mountain aloes in the Botanical Garden seem to have fallen for this reason in the past few months and I was told of Quiver trees (Aloe dichotoma) and Butter trees (Cyphostemma currorii) that did not survive the unusually wet conditions.
Different aloe species growing in close pro-ximity to each other frequently hybridise, for instance the mountain aloe may crossbreed with the trunk less Aloe zebrina and it is therefore not always easy to identify these plants.
The flowers contain large amounts of nectar as well as several minerals and vitamins. It may be eaten directly off the plant or boiled and ea-ten. The flowers may be pounded into a soft, sticky mass, shaped into patties and dried for later use. Various sunbirds, grey louries and other birds, moths, flies and other insects are attracted by the nectar. The plant is frequently affected by white scale and visited by spiders, plant lice, various ant species, weevils and pa-rasitic wasps.

Aloe is a well-known folk remedy. The juice from the leaves is used to treat eye problems. A watery decoction of the leaves alleviates venereal disease without however effecting a cure. Allegedly, a daily dose of this watery decoction prevents malaria. The powdered dry leaves cure wounds. In days gone by farmers would place cut up aloe leaves in the drinking troughs to protect their animals against ticks and lice, a treatment, which I also found useful for lice on chickens. Boiling the cut up leaves in water and straining the gelatinous juice provides an effective purgative for man and beast.
Research brought to light that due to the great popularity of aloe flowers with insects and other animals, a mere 20% of the seeds actually ripen. The mountain aloe was thus declared a protected plant and may not be injured or dug up. Plants are available from the nurseries of the Forestry Directorate at Okahandja and Grootfontein. They grow well, especially on alkaline soils. They can also readily be raised from seeds. During the first years they should be protected from frost and they should be watered sparingly.

Names: A. Windhoekaalwyn, bergaalwyn; G. Bergaloe; H. Otjindombo. N. augoreb; Nd. Endombo. The botanical species name littoralis means 'growing along the beach/river banks'. In Namibia this aloe does not occur along the coast at all. However the first specimen of this plant was collected by the botanist Welwitsch on hill slopes facing the ocean north of Luanda in Angola and was thus named accordingly.