MAY TALK REPORT
Dr Ernst van Jaarsveld, horticulturist and curator of the Kirstenbosch Conservatory: Cape Agulhas to Angola Expedition
Rea Borcherds
A large audience turned out to enjoy the privilege of hearing world expert botanist, horticulturalist and author Ernst van Jaarsveld give a comprehensive overview of his explorations all around southern Africa in search of succulent plants.
Ernst recently retired from Kirstenbosch after 41 years as curator of the Conservatory there. He is recognised as the most prolific plant collector in Kirstenbosch’s history and also the most productive publisher of books and articles on South African flora.
The title of his talk, ‘From Agulhas to Angola’, indicates the broad sweep of his explorations in search of succulents, covering no less than eight separate excursions: the Western Cape, Cape Point Nature Reserve, Kouga Dam, Mbashe River, Knersvlakte, Richtersveld, Namibia and Angola.
These explorations were a rich hunting ground, with an enormous variety of climatic and geological conditions – including cool coastal fynbos, lush Transkei river systems and gorges, barren rock faces, harsh desert terrains and blistering dunes. In his relentless pursuit of succulents Ernst scales the sheerest of cliffs, and he and his colleagues face the most physically daunting of challenges. Their rubber ducks were swamped when the previously shallow Mbashe River unexpectedly came down in flood, dumping them in the gushing rapids; and they very narrowly escaped from an angered hippo in the Great Fish River. The hippos apparently escaped from adjoining nature reserves and now threaten anyone who comes too close.
Ernst glosses over such potentially tragic episodes, focusing on the hundreds of fascinating and often unknown specimens that he finds and photographs. On the Kouga Dam, looking for something else, he came across a new little aloe and a new Gasteria glomerata. He finds river systems like the Mbashe fascinating because they have endemic plants which only occur there and nowhere else. In the cliffs near the Colleywobble Electrical Power Station he found the beautiful Cotyledon pendens with its hanging flowers, aptly named cliff bells; and a new Bulbine thomasi, which he named after Vicki Thomas.
The great variety of shape and size of succulents is due to the influence of their different habitats. Ernst often names his finds appropriately, like the Ruschia promontori, which he discovered on the tip of Cape Point where it juts out into the ocean. Cliff faces are of particular interest to him, because they are an unknown and unexplored habitat. Plants that live on cliff faces adapt to the cooler, moist conditions and also lose their defence mechanisms of spines and chemicals, because the rock crevices are sufficient defence. Many develop a pendant habit, like the Bulbine pendulus he found hanging from the cliff at Aughrabies. (Ernst himself, no doubt, was also to be found hanging from the cliffs!)
In thickets, where animals roam, plants develop fierce spiny thorns to prevent being eradicated. Some, like the spekboom, however, allow themselves to be trampled underfoot because that is how they proliferate; each leaf being able to generate a new plant.
Plants in summer rainfall areas tend to grow larger, while in winter rainfall areas plants are inclined to dwarfism. In the arid Richtersveld where the winter sun is low, the plants are minute, creating a Lilliputian world. They snuggle down into the rock crevices and make use of the surrounding soil and rock for absorbing the warmth of the sun’s rays and any moisture that is available.
In the dry hostile environment of the Namib where rainfall is very low, plants are fog-dependent. They develop various methods of trapping fog and channeling it down to their roots, and often have very broad leaves. The biggest is the Welwitschia, which occurs only in Namibia and Angola, and is also botanically unique in its physical structure and functionality. It never loses its leaves nor develops new leaves, as that would rob it of too much energy. Instead the leaves just keep on growing like a conveyer belt.
Ernst calls himself a plant lover and on his expeditions all cherished new finds are immediately added to his travelling nursery for future propagation. He has been responsible for finding and naming hundreds of new species in his career so it was a fitting end to this stimulating evening to hear the announcement by Dr Brian Huntley that the Royal Horticultural Society Medal had been awarded to Ernst van Jaarsveld.
Since his retirement from SANBI Ernst has found a new home at Babylonstoren, near Franschhoek, where he has immediately set about literally moving mountains and creating a new indigenous garden. He is in the process of setting up an Internet site offering gratis gardening advice on any topic to all who seek it. It is good to know that everyone will be able to continue benefiting from Ernst’s prodigious knowledge.
