Kalahari desert :: Plants of the Kalahari desert. Plants in the Kalahari desert

Plants in the Kalahari desert

The important plants in the Kalahari Desert fit roughly into one of two groups:

Plants in the Kalahari desert that are important because they occur mainly in the Kalahari desert or in Kalahari desert sand, such as the Camel thorn.

Plants in the Kalahari desert that occur elsewhere as well, but which are so abundant or typical in the Kalahari that you cannot ignore them, such as the Shepherd tree.

Compared to the incredible wealth of species of the Cape Macchia or "fynbos", or even the Karroo with its succulents, the plants in the Kalahari are surprisingly "species poor". No members of the Aloe family, so ubiquituous elsewhere in South Africa, occurs in the Kalahari, and very few above ground succulents. The bushmen candle Psilocaulon spp. and the "Ghaap" Hoodia spp. are the rare exceptions to this rule of thumb. (Yes, it is the "Hoodia" of recent pharmaceutical fame, the "Bushmen wonder plant, used as a diet aid!).

Shifting sand seems to be a major barrier to many species. Plants in the Kalahari tend to have extremely deep roots (up to 40 m deep for the Camel thorn) and a single species seems to have various growth forms that can exploit water at a specific depth. Many plants in the Kalahari, for instance, occur as both a large tree and as a shrub. In most cases this is controlled by shifting sand and by animal and other damage, and not by age.

An alternative to "deep and hidden" survival strategy, is followed by plants such as the "devil thorn" Tribulus spp. that develop extremely rapidly and completes its whole life cycle from germination, to flowering to seed-formation, within as short a period as two weeks.

Trees

Camel Thorn tree Acacia erioloba

The Camel Thorn tree, or "Kameeldoringboom" in Afrikaans, is without question the best known of the trees or plants in the Kalahari desert. Depending on growth conditions the camel thorn tree can become an immense tree of up to 10 m high, or less commonly, a smaller, multistemmed shrub. Strange as it may seem, the "Camel" that the name suggests, is not the Dromedary camel, which do occur in the Kalahari but which is an imported animal, and bred in captivity. The name "Camel thorn" actually refers to the love of Giraffe's latin name Camelopardus or Afrikaans "Kameelperd" meaning "Camel-horse", as can be seen from the old botanical name of the tree, Acacia giraffae.


Camel thorn tree	Camel thorn tree, detail pods

The Camel Thorn tree has a very hard and dense wood, but not so hard or so dense as leadwood or Lignum vitae. It is used for many purposes, and is the preferred fire wood for a "braai" or "braaivleis", which is the Afrikaans word for a Barbeque (BBQ). In the Kalahari, at least in South Africa, these plants in the Kalahari desert has been a protected species under the Forestry act, for the past two years, so please do not braek of branches or twigs, or even, like in the old days, pull over a large half-dead tree. It is only sale of the wood that is forbidden unless you have a permit, not posession.

Although this may serve the purpose of protecting the Camel Thorn tree amongst the plants in the Kalahari desert, this has displaced the burden of supplying fire-wood, to other trees and or and plants in the Kalahari desert. At best, invader species like the Rhigosum or the Alien Prosopis or "Mesquite" from the Cowboy books, is used as an alternative firewood, but where these invaders have been eradicated, other local species of plants in the Kalahari desert, such as the Shepherd Tree now carries the brunt. This has happened recently around Askham, where Prosopis trees was eradicated by Working for Water, an initiative of the Department of Water Affairs to eradicate water-greedy exotics plants in the Kalahari desert, from water courses.

Perhaps the most remarkable aspect of the Camel Thorn tree, is its seeds which forms a large crescent (or "half-moon"), up to 4 or 5 inches from end to end, and covered by a fine grey down, almost like that of a camel. These pods, of which a mature tree (80 years plus) can produce 500 kg in a season, contians a fine nutritious powdery inside, that surrounds a number of hard and shiny seeds. In severe drought periods, these seeds makes up a major part of the survival rations of most Kalahari animals and are a very important survival food amongst the plants of the Kalahari.

Shepard tree Boscia albitrunca

The Shepard tree occurrs much wider in South Africa and Africa than just the Kalahari, but this tree with its white bark and small dark-green leaves, comes to its right especially in the Kalahari, amongst the plants in the Kalahari desert. It is one of the few trees that will actually grow on the slopes of a dune, and in the Kalahari, where existence is a strugle and shifting sands constantly exposes roots, while heavy grazing distorts the tree, the Shepperds Tree seem to have a special beauty of its own. Of all the Kalahari trees, this is my personal favorite.

kalahari - Sheperd tree - Boscia albitrunca

Besides its beauty and the luxury of its shade, the shepherd tree is used by man and beast in a variety of ways of which I mention only a few:

The fruit or berries are delicious and can be eaten raw or as a jam or in yoghurt
The roots are used to prepare a coffee substitute
Roots are boiled to produce a sweet syrup
All parts of the plant have medicinal, flavour or food uses
The roots are ground and used as a flour or porridge
The roots are used to preserve butter and milk

Grey Camelthorn (Acacia heamatoxylon)

In the Southern parts of the Kalahari, this tree normally occurs as a multi-stemmed shrub although the odd large tree can be found in the dry river beds. In the Kalahari desert Savannah or "sand flats" of the North and East, the grey camel thorn more commonly occurs as a tree of up to 8 m high. As its name suggests, its foliage has a grey tinge. The seedpods of this tree tend to be thinner and rounder in shape than the crescent shape of the true camelthorn, with a distinct constriction between the seed-pods, to give a string of beads effect. The tree form, but not the shrub form, forms hybrids with the true camel thorn, of which I don't yet have details.


Grey Camel thorn tree	Grey Camel thorn tree, detail pods	Grey Camel thorn tree, detail leaves and flowers

Black thorn Acacia mellifera subspecies detinens

This is perhaps the most conspicuous shrub in the Kgalagadi Transfrontier Park and elsewhere in the Kalahari desert. It forms thick clusters. This seems to be a natural occurence, and not necessarily due to over-grazing.

Driedoring ="Three-thorn" Rhigozum trichotomum

This small shrub is typically found on an calcareous substratum. It is also found along rivers, pans and other area where brackish water forms pools. It is characteristically found on the fringes of the vegetation around pans