Bosch Luys Kloof's

Iconic FLORA

Plants growing in the inhospitable conditions of the Karoo are faced with challenges which range from rocky soils, attack by plant predators, competition by other species to the desiccating sun and comparatively low rainfall. One fantastic aspect of Bosch Luys Kloof is the relative lack of alien plants, many of which would struggle for survival under these conditions. The other is the great diversity of locally occurring plant species both large and small which have evolved adaptations allowing them to survive in these conditions. It is very difficult to single out only a handful, but here are five species that, each for their own reasons, we feel deserve a mention...

Nestled inside a mountain wilderness, at the transition between the Little and Great Karoo, lies Bosch Luys Kloof. The plants that grow and thrive in this valley and surrounding mountains are equipped with a series of adaptations which enable them to survive against all odds.

a great diversity of locally occurring plant species
both large and small.

Bitter Aloe – Eng, Tapaalwyn – Afr (Aloe ferox)

Aloe ferox deserves a mention here as it is one of the first plants that really stands out above the rest as you round the bend at the top of the Bosch Luys Kloof pass before being greeted by the iconic view down the valley and beyond which has become our logo. Not only do they stand tall, some growing to 3m, but adorn the veld in winter with beautiful yellow to bright orange-red flowers crowning the very top of the plant, like branched candles. Aloe ferox fits right into one’s mind’s eye when picturing iconic ‘Karoo’, along with windmills, dorper sheep, donkey carts and small labourers’ cottages.

The tubular individual flowers are pollinated by sunbirds and sugarbirds, at Bosch Luys Kloof by the Malachite Sunbird and Lesser Double-Collared Sunbird, and Cape Sugarbird in Seweweekspoort where they grow abundantly as well.

Aloe ferox is indigenous to South Africa, and has a wide distribution from Swellendam in the Western Cape to the Eastern Cape and southern Kwazulu-Natal, northwards through the Karoo into the Free State and Lesotho.

These plants stand proudly, as watchmen, at the transition between Arid Renosterveld on the plateau at our main gate, and the Guarri-Spekboomveld descending into the valley below. The renosterveld verges on Grassy Fynbos on our To Hell ’n Gone 4×4 route towards the lookout over Gamkaskloof, a habitat type which has evolved to cope with and indeed rely on frequent veld fires for carbon and nutrient deposits, germination and resprouting. Aloes have massive succulent leaves, those of A ferox are around 50cm long and weigh around 1.5 to 2kg each, with prominent teeth on their margins, and are fire retardant. The plant has a woody stem, but old leaves remain on the stem for many years and are not flammable which help to protect the plant against veld fires.

Aloe ferox is a hardy plant and is especially suited to areas that are water restricted. Of the +-350 species of aloe, a few have been used as medicinal plants, but only A ferox is harvested to manufacture commercial medicinal and cosmetic products. At least three rock art sites have been discovered where the San depicted representations of aloes, illustrating that they likely utilised the medicinal value of A ferox years ago already. In years gone by, Xhosa mothers in the Eastern Cape would use the bitterness of A ferox during the weaning process by rubbing it on their nipples in order to get their babies to stop breastfeeding.

Derivatives of the juices extracted from Aloe ferox leaves contain an abundance of amino acids, minerals and vitamins that are essential in the maintenance and health of the largest organ in the human body, the skin. For this reason, various skincare and cosmetic products are produced using A ferox, and Aloe bitters (another derivative of A ferox) is a known laxative and purgative.  

Sweet Thorn – Eng, Soetdoring – Afr (Vachellia karroo = Acacia karroo)

This is the only species in the genus Vachellia (previously and more commonly referred to as Acacia) that occurs naturally in the Karoo, though is also widespread throughout southern Africa. This thorny tree, which grows to a height of 5 to 12m, survives in dry areas where temperatures exceed 40°C. It can be easily identified by the long white thorns which grow from the base of the leaf stalk as a deterrent against plant predators. Fulfilling a protective role, the thorns are often more abundant, and larger lower down on the tree as well as on younger trees, where predation by browsers is more prevalent. Small yellow sweetly-scented flowers are pompom shaped and attract many pollinators, in turn attracting insectivorous birds, and their nectar is known for producing good honey.


The Sweet Thorn is an important fodder plant providing a staple diet to Kudu and other browsers at Bosch Luys Kloof. The sickle-shaped seed pods are a great source of protein and both pods and leaves are readily browsed by game. These bushy trees form dense thickets along the dry river banks and alluvial floodplains of Bosch Luys Kloof, providing great nesting sites for various bird species as well as shelter for Kudu, Common Duiker and many other species of fauna on the Reserve. Sweet Thorn extract water and nutrients from deep underground with their long tap roots and the presence of these trees in a dry area is often an indicator of good underground water. Their ability to utilise underground water, paired with their root nodules which promote beneficial nitrogen-fixation and small leaves (reducing water loss in hot conditions through transpiration) allows them to survive very low rainfall years.

Vachellia karroo also have a chemical defence which protects them against excessive browsing by herbivores as well as against plant pathogens. Plants increase their levels of tannins (polyphenolic compounds) in their leaves when ‘attacked’ or browsed on by Kudu for instance and in turn become less palatable to their herbivorous predators forcing them to feed only for a while before moving along to the next tree. Consuming high levels of these tannins is toxic to browsers. It is also suggested that individual plants release ethylene when browsed on, which in turn signals nearby trees to increase their leaf tannin levels. Browsers will often move against the prevailing wind direction when feeding to avoid browsing on plants that have received these chemical signals and already have tannin rich leaves. This is a form of chemical signalling or communication between plants.

A very useful plant, the tannin rich reddish bark yields tannins used to dye leather, the sweet gum which exudes from the plants stem when damaged is used in the confectionary industry and as an adhesive, the seeds can be roasted and used as a coffee substitute and of course the wood is very popular as fuelwood and for making charcoal in South Africa.

Namaqua Rock Fig – Eng, Namakwa-vy – Afr (Ficus cordata)

There are around 850 species in the genus Ficus worldwide, and around 26 species indigenous to South Africa and Namibia. One of the most impressive and eye-catching trees growing at Bosch Luys Kloof is undoubtedly the Namaqua Rock Fig, or in latin Ficus cordata.

These beautiful trees grow to about 10m high at Bosch Luys Kloof but can reach impressive heights of 20m! With their pale grey trunks and branches, and impressive wandering roots which can extend for long distances to reach water at ground level (as they often grow on rock outcrops or cliff faces) or into crevices in the rock to obtain moisture, they are unmistakeable. They grow in the western arid parts of South Africa, through Namibia to southern Angola, and are able to tolerate very dry conditions. Likely one of the most impressive features of this species is their long, powerful wandering and rock splitting root system.

As is the case with many other kinds of fig trees, F cordata relies on its own specific species of wasp for pollination. Their tiny flowers, both male and female, line the inside of the urn-like fig itself, with the fruit actually being an enclosed inflorescence or flower head referred to as a syconium are pollinated by the equally tiny female wasp Platyscapa desertorum. The female wasp enters the enclosed fig and lays her eggs, in so doing pollinating the flowers. For this reason the fruit of F cordata are not fit for human consumption as they are often insect laden.

The Namaqua Rock Fig bears small stalkless figs around 8mm in size that ripen from light-green to reddish-brown in spring to summer. Fruits are dispersed by frugivorous birds, baboons and monkeys amongst others. At Bosch Luys Kloof the Red Winged, as well as Pale Winged Starlings, are especially fond of the fruit of the Namaqua Rock Fig. Seeds that germinate in cracks or crevices in cliff faces are safe from herbivores.

Beautiful examples of these trees can be seen as you descend the Bosch Luys Kloof pass and continue towards the lodge.

Pork Bush / Elephants Food – Eng, Spekboom – Afr (Portulacaria afra)

Spekboom needs no introduction here, as it has become world-renowned as a ‘wonder plant’ due to its hugely beneficial role in helping to keep the fragile balance of our atmosphere where it should be. We are very lucky to have at least 1000Ha of Spekboom covering the reserves slopes. This evergreen succulent-leafed shrub prefers the north facing slopes and exposure to full sunlight, year round. Even in the driest of conditions, Spekboom remains lush and green. There are a number of noticeable examples on the approach to the lodge where the preference of Spekboom for north- and east-facing sunny slopes is very evident.

With more and more focus on global warming and increasing levels of CO2 in our atmosphere, Spekboom is enjoying a lot of limelight, and deservedly so. Often, however, it is believed that what makes Spekboom so special is its ability to produce large amounts of oxygen, but in fact it is the role of Spekboom as a ‘carbon sponge’ and its ability to sequester massive amounts of CO2 out of the atmosphere that gives it renown. One hectare (ha) of Spekboom will typically sequester (remove from the atmosphere) between 4 and 10 tonnes of CO2 per annum – this means the Spekboom growing at Bosch Luys Kloof is sucking between 4000 and 10000 kilograms of CO2 out of the atmosphere, every year. This is a significant amount indeed. Amazingly, hectare for hectare Spekboom rivals the well-known Amazon rainforest in its ability to remove CO2 from the atmosphere.

Spekboom is readily browsed by Kudu and Eland at Bosch Luys Kloof. A remarkable plant, with small succulent leaves that are fire retardant and edible to humans, said to boost the immune system and have also been chewed in the Eastern Cape as they stimulate lactation in breast-feeding women. The small pink flowers are not often seen on Spekboom, but produce nectar which makes excellent honey.

During photosynthesis, plants breathe CO2 in and O2 out through small openings on their leaves called stomata. If the stomata are open and the atmosphere is dry and hot, plants will lose H20 through these openings. Spekboom has the incredible ability to close these stomata during the day in hot dry conditions, and open them at night to reduce water loss through the process called transpiration. It is also amazingly able to switch between two different methods of Carbon Fixation based on climatic conditions, namely C3 or CAM Carbon Fixation. When conditions are hot and dry, stomata close during the day and CAM Carbon Fixation is used. When more moisture is in the air, C3 Carbon Fixation is used.

There are numerous Spekboom rehabilitation projects on the go in areas where this very important succulent-leafed bush previously grew abundantly but due to bad farming techniques and ignorance has been removed. Bosch Luys Kloof counts itself lucky to have such an abundance of Spekboom on the reserve.

Karoo Gold – Eng, Geel Berggranaat / Granaatbos – Afr (Rhigozum obovatum)

Karoo Gold (Granaatbos in Afrikaans) is aptly named and deserves a mention here due to its resilience in dry times, and optimization of rainfall in wetter times. Also purely due to the aesthetics, as the Karoo can go from a dull and dreary grey-brown landscape to a spectacular patchwork of golden yellow when these plants flower in comparatively rapid response to good rains. This shrub can grow up to 2m tall, with long thin twiggy and spiny stems, and is very drought-tolerant. In dry times, Karoo Gold appears devoid of life, going almost dormant and conserving energy, a dull dark grey mass of thin dry pointed stems, however it is the transformation of Karoo Gold after good rain that sets it apart.

Plants respond very quickly to rain after drought, and can be covered in beautiful flowers within a week or two after good rains, really covered in flowers. They maximise the chance to reproduce and attract pollinators in response to enough moisture, but only after the stress of drought. The transformation is spectacular and they adorn the veld in a bright yellow hue, glistening gold in the light of sunrise or sunset. They flower mainly in spring and summer, but will respond to rain throughout the year, transforming from dead-looking sticks to lush small green leaves and an abundance of flowers in an alarmingly short space of time.

Capitalizing on the moisture, the flowers when germinated are followed by flattened pod-like capsules that bear the seeds, and make a sound similar to that of a rattle-snake in the wind.

Young leaves are well browsed by game, especially by Springbuck at Bosch Luys Kloof but also Kudu and Steenbok.

Plants in the Karoo epitomise resilience and hardiness,

 forever in competition with each other, their predators and pollinators. They’re equipped with defences, evolutionary traits and adaptive characteristics which together enable them to survive in this harshly beautiful mountain wilderness.

For more information:
+27 23 581 5046