Colours of Wildlife: A Trip to the Potlake Nature Reserve
Created | Updated Sep 30, 2023
A Trip to the Potlake Nature Reserve
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
On the 7th of September 2023, our group headed to the Potlake Nature Reserve as part of an exploration of the region of Sekhukhuneland. We were: Bronwyn Egan, curator of the Herbarium of the University of Limpopo; two students, Prince Molokomme and Kagiso; Ntsakisi Masia and Adelaide Lekota, working to collect seeds for the Millennium Seed Bank; and me! At the reserve, we were joined by a couple of students who were working there, mainly on the animals; we were able to tell them quite a bit about the vegetation of the reserve. They in turn were able to guide us to some very interesting spots!
So first of all – the Potlake Reserve is a decent-sized nature reserve in the vast region that is Sekhukhuneland. The name is pronounced 'Po-tlah-kee' (the 'tl' sound may be a bit strange for an English speaker but not unusual in many languages over here), rather than 'Pot-lake'. The reserve is centered on a range of hills oriented in an almost exact east-west direction. The hills are striking and visible from the main road: they are made of very dark rocks that seem to have been stacked by giants. It looks very desert-y, with not much vegetation visible from afar, but if you go in, you actually find a high diversity of very unusual plant species. The region is quite dry; the black rocks get scorchingly hot from the intense sun, even in winter; the soils are high in heavy metals, which can be poisonous for many plants. It is therefore a unique selection of plant species that are able to survive and even thrive there. Here you see Ntsakisi and Adelaide posing in front of some strange Euphorbia cooperi plants, tree-like succulents that dot the hills in abundance.
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What is amazing about Potlake is that it has connections, in terms of its vegetation, to areas very far away. I show you three species here to illustrate this. The first is the distinctive tree, Balanites maughamii, the Torchwood. This tree occurs mainly in the Lowveld, which is the easternmost section of Limpopo Province. What made it possible for these trees to spread inland to Sekhukhuneland, is that the Olifants River, a major feature of the northern part of Sekhukhuneland, penetrates the Transvaal Drakensberg Mountains. Thus the valley of the river has created a corridor that enabled trees and other plants to spread inland from the east. Also, Sekhukhuneland is quite low-lying, making it hot enough for these lowveld trees to survive. Torchwoods are amongs the tallest trees in this very dry region.
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Another interesting link is the Worm-Cure False Thorn, a medium-sized tree with beautiful white flowers that were conspicuously blooming in the dry veld on the day. This tree I mainly associate with the Limpopo River Valley, which is far to the North. Again, here we have a very hot and dry region, quite similar to the Limpopo Valley. Mountain ranges and high-lying, cooler and moister land now separate these regions, but there must have been ways in the past to 'travel' over these unfavorable regions from the north and/or from the east. Other typical Limpopo Valley plants that also grow in Potlake include Star Chestnuts and Sesame Bushes.
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The final link was something we found and did not expect! This was the low, yellow-flowered shrub you see here being inspected by almost everyone. This is Lasiosiphon polycephalus, the Besembossie ('Little Broom Bush'). It is actually understood to be a resident of the dry Karoo and the Kalahari Desert, hundreds of kilometres away to the west and south! I think we might be the first botanists to record it here. So here we have a link with the Karoo – and not entirely unexpected, since another shrub, the Karoo Gold, Rhigozum obovatum (interestingly, also yellow-flowered) was also recently discovered here, as well as in a few other places. The link here must go back to quite an ancient time, when the whole country was much drier. Now, these drought-adapted shrubs manage to hang on in the deserty-climate of Sekhukhuneland.
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Another feature I mentioned is the presence of heavy metals in the soils. This makes the region very popular with mining companies, and a large chromium mine (which happens to be illegal) is visible from the reserve. But heavy metals are toxic to most plants. Those who can tolerate these high metal levels, though, can become dominant. This we saw for ourselves when we found these Helichrysum candolleanum plants. They're members of the Everlasting genus, in the Daisy family. We found extensive patches that were almost completely barren except for these plants, and some grasses and scrubby, stunted trees. These Helichrysums can tolerate heavy metals, and even concentrate them in their own tissues. They are amazing for being very round and grey, from a distance looking like rocks, but closer inspection reveals them to be covered in myriads of pretty flowers!
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Other plants showing adaptations to the climate I show you here. The corkwoods, of the genus Commiphora, are (mostly) small trees that can tolerate great heat and drought. One of the nicest is the Satin-barked Corkwood, Commiphora tenuipetiolata, which has lovely smooth, cool, white bark that flakes in thin, soft strips. This flaking bark reflects much of the intense sun and the various layers keep the main living tissues inside the trunk, branches and twigs cool. The corkwood genus occurs from the dry and desert regions of Southern Africa northwards to the Horn of Africa and the Arabian Peninsula. The myrrh mentioned in the Bible comes from the gum exuded from a Commiphora species that occurs around there.
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The Sekhukhune Greenstem, Adenia fruticosa, is a rather grotesque member of the Passion Flower family. It's flowers aren't much to look at, though, and its fruits, while attractively orange-red, is poisonous to humans. But it has an immense trunk, the tissues of which store a lot of water. The one you see Kagiso sitting on here, is a giant we found fully exposed on one of those dark-rocky hills. The sun bleached the normally green basal trunk quite white in this one, but it was healthy and had vigorously sprouting tendrils and leaves which you can make out behind and to the right of Kagiso. I also show you a plant with the proper green stem, which we found a bit to the west of Potlake, to show you what it looks like in a more sheltered position. Prince posing next to it gives you a sense of its size.
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Finally I show you the Bowstring Hemp, Sansevieria hyacinthoides. As the name suggests, this plant has strong fibres that can be used for making bowstrings, as the San people of old did. The leaves are very thick and tough, and can withstand dessication, intense sunlight, and abrasion from weather and animal activity. Several Sansevieria species occur in Africa and parts of Asia; some are popular garden and indoor container plants for their attractively marked leaves and overall hardiness.
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This was just a bare-bones introduction to the plants of Potlake for you all. It was for us as well! We had just one day, and couldn't do nearly the amount of exploring we wanted to. We barely even got into the hills! I hope we will return soon. We saw it during the driest part of winter; it would be interesting to compare once we've had some good rains – which should happen any day soon now!
