We drove west from Stellenbosch heading over towards the formidable mountains that flank the eastern boarder of the Cape Flats. Our intentions were to cross over the peaks and make our way into the appreciably drier semi desert region to the east. On the drive today we would pass through fynbos elements and into succulent Karoo. As we climbed into the mountains our road meandered up over Du Toitskloof Pass. Views at the high passes extend east across the Cape flats and through a haze Table Mountain could be made out in the distance. The Hawequas Mountain Range striate from north to south giving way to a series of valleys and mountain chains that continue to build until the high plateau that dominates the interior of South Africa is met. In the winter, and all year long, these mountains are major barriers for the prevailing weather fronts, rich with ocean moisture from being able to reach the heights. The farther east one travels from the Cape flats the more pronounced is the rain shadow effect.
The effect of this weather pattern causes the mountains in this region to have a continued cloud veil that often gives the mountains a cap, shrouding their high domain from view. This also creates continued rainfall events in the high regions that feed the streams that cascade down and support the agricultural and horticultural industries in the valleys of the Cape region. As mentioned in earlier posts, these gradients of precipitation, adiabatic cooling, topography, and elevation create highly unique and niche areas that drive plant speciation and endemism.
Karoo National Botanic Garden sits to the north of the town of Worcester. Its collections focus on the flora that are adapted to the desert conditions of the succulent Karoo biome. These plants tend to have adapted CAM photosynthesis and thickened cuticles on the leaves to be able to deal with the harsh conditions. At Karoo we met up with the horticulturalist at the botanic garden. We started with a back of the house tour of the formal collections.
As has been a pattern in the vernacular of the botanically trained in South Africa, it seems that “plant collections” often refer to the holdings that are typically unavailable to the casual garden visitor. Kept out of reach, typically behind locked gates and safely stowed away in greenhouses, these “collections” tend be the ones of high scientific and at times economic value. With many highly prized plant species and genera only found in South Africa this mentality of precaution becomes more of a practicality when one considers the typical size of bulbs or succulent plants. While a visitor of an arboretum in North America might find practical limitations in walking off with a prized mature tree specimen stuffed in his or her pocket, the same restrictions do not apply when an ancient succulent may be a mere few inches in diameter. With an air of concern for the continued unscrupulous actions of plant poachers, the heightened security at botanic gardens feels no more an affront of one’s decency as a necessary precautionary measure. In many gardens the plants on display that are available to the public might only be the more common species with the more sensitive materials kept under a watchful eye.
The formal collections extend through several greenhouses and are focused on the major genera that are found in the Karoo biome. These include, Lithops, Conophytum, and Haworthia primarily, with other sorted genera. Plants exhibit a vast array of diversity in phenotypes, size, age, and color. These plants tend to be small in stature, so the greenhouses are packed full of hundreds of specimens showing the range of the various genera. It is no surprise that the Haworthia has taken off as a horticultural interest and oddity around the world and is now often a subject of over-collecting in the wilds of South Africa. As with all the national botanic gardens, conservation and preservation of species of concern are the chief responsibility and mandate for the garden. This is strongly reflected in the diversity of the collections.
As was also noted in the visit to Kirstenbosch, the absence of a unified plant record system or even a systematic way of conducting plant documentation was observed. For any collection, especially one with a conservation focus, plant documentation should be a chief concern in maintaining the integrity of a collection. This appears to be a challenge with the national botanic gardens and for whatever reason is not a priority for the national organization that oversees them. It appears to have to do with the expansive bureaucracy of SANBI that makes it challenging for administrators who make decisions to communicate with practitioners, who ultimately have to implement the policy and the decisions that people higher up in the management chain make.
After seeing the collections in the greenhouses we ventured outdoors to explore the garden proper. The collections meander across the bottom of a small mountainside. We had strong displays of Drosanthemum bicolor which show off why they have been winners as horticultural plants. The level of horticultural care varied across the garden demonstrating the varied capacity and training of the horticultural staff in South Africa. A forest of Kokerboom (Alodendron dichotema) grace the side of a hill in the garden. These plants in the Asphodeloideae family tend to be a bit temperamental when it comes to exposure. As was noted in the my earlier adventure to the native Kokerboom forest to the north, the Alodendrons seem to almost solely grow on one side of the sloping mountains. This was noted in the botanic garden as well when plants growing on a southern exposure were compared to specimens on a northeast exposure. Perhaps this has more to do with transplant time, age or original plants but the contrast was still stark. As the specimens develop over time and slowly grow, and with a bit of luck, this hillside will create “forest” in the coming decades. An assortment of the Mesembs (Aizoaceae) were showing their bloom and larger than life colors. The last adventure that we took was a hiking up to an unmanaged natural area into the mountains that surround the garden. The abundance of desert flora was presented to us with some of the most interesting succulents to be found hidden under larger shrubs. Often they would only be observed when looking sideways or moving a shrub to the side revealing the small structures close to the ground. These small protective microclimates give the succulents a fighting chance. Even small rock shelves or soil filled crevices provided just enough protection for these plants to make their homes.
Heading back to Stellenbosch we ventured forth to a different mountain pass known as Bainskloof. This small road is only accessible to smaller cars, prohibiting large trucks from using this route. These restrictions are in place because the road tightly winds along a river rushing below, with steep drop offs and rocks overhanging the road. This pass, among many others across South Africa, were constructed by the Bane family. Andrew Geddes Bane emigrated from Scotland in 1816 and over time it was revealed that he had an unprecedented ability to navigate, scout and engineer safe routes through the South African mountains. Andrew was also a keen geologist and was the first person to develop a geologic map of the country. Andrew’s son, Thomas Charles John Bane, also developed into a road engineer, constructing over 900km of road across the country. Between the father and son, the family is credited for building many of the major roads and passes across the country allowing access to South Africa’s interior and subsequent development of these areas. Today, mountain pass tourism is a promoted activity in the county with guides available for adventures who enjoy taking the scenic route.
- Baneskloof Pass is of special interest; not only because of its scenic nature, but also because of the rare plant communities it holds. Baneskloof is one of the few locations where a rather rare and unusual Drosera species grows, representing one of Stellenbosch University Botanical Garden’s priority species for conversation. The details of this plant will wait to be explored at a later post for we are planning a trip to attempt to locate one of the few remaining populations of this fascinating species in the near future.