The visitor to “the most beautiful garden in the world” , picnicking on the lawns or contemplating life and beauty from one of the shaded benches in the garden, sees the end product of a great deal of background thought, knowledge, effort and labour that he is probably little aware of. I was delighted to be privy to ‘what goes on behind the flowerbeds’ in Kirstenbosch when invited on a media field trip by Anthony Hitchcock, Program Manager of Nursery, Plant Collections & Threatened Species at Kirstenbosch.
After introductions at the Gardens offices we set off in two vehicles up the track from Constantia Nek towards the back table of Table Mt with all the required permits in place. Permits are required from SANParks or the landowners of the areas selected for the harvesting of the plant material (cuttings) and seeds, as well as for vehicular access to Table Mountain. As we gained height the pine forests gave way to the rich variety of fynbos covering our iconic mountain. Half way up we stopped to watch as Ntsindiso Zide, Specialist Nursery Groundsman for the Erica collection, took cuttings from Erica tenuis growing in minute pockets of soil on the south facing cliffs. “In winter the rains run down these rocks giving life by providing the ideal moist habitat for these plants to grow,” said Ntsindiso.
Having snipped off a branch of the Erica with disinfected secateurs, Ntsindiso pulled off the tiny end sprigs, about 2-3cm long, leaving a heel at the base of each cutting. “The cutting needs to be soft and springy. If it is brown and slightly woody at the bottom then it is too old a root,” he explained. The cuttings are immediately placed into moist, clean plastic bags and labelled with their botanical name together with vital information such as the GPS co-ordinates of the plant’s locality, details of the surrounding vegetation, the geology – whether growing in limestone or sandstone – and the time of the year in which the cutting or seed was collected. Once back at Kirstenbosch, all the collecting information is processed and stored in a computerized database. An accession number is given to each plant and this number will accompany the plants on their own permanent labels for the rest of their lives. Kirstenbosch staff requiring information about the plant simply have to key this accession number into the database. The database is comprehensive and critical for recording as much information about each species collected for distribution records: the habitat it grows in, soils, moisture and anything else important for determining how best to grow the plant. The data based records are also given to the conservation landowners such as Cape Nature for their records as part of the requirements for being granted a plant collecting permit.
Further up the track we stopped alongside a clump of Leucospermumcordifolium (pincushions) which incidentally are not endemic to Table Mountain. Louise Nurrish, Kirstenbosch horticulturist whose focus is on Proteaceae and Restionaceae, described the methods of taking cuttings from the protea family. Following a very strict programme to prevent disease, cuttings are only taken from healthy plants. “Leucospermums are prone to many diseases including a disease called Elsinoe. Cankers attack secondary growth causing the branches to distort and flowering to be drastically reduced. The disease spores spread rapidly through water, often during unseasonal summer rainfall. If necessary rather propagate infected plants from their seeds which are much less likely to carry the disease.” Semi hardwood cuttings of Proteaceae are taken from December through to March.
I was fascinated to hear from Anthony Hitchcock that cuttings of Gymnosperms have to be taken from the top of the plants otherwise they will keep growing sideways. Even when growing against a support, if the plant has been propagated from a downward hanging branch the new plant will grow downwards as soon as it is unsupported.
Growing in the vicinity of the Woodhead Dam on the top of the table are tussocks of restios of different sizes, the seeds of which ripen at different times. We watched as Zitobile Sikova, Specialist Groundsman of the Restionaceae, explained the collection of the seeds of the large Elegia mucronata which are harvested at the end of February. “Some restio seeds germinate well when newly harvested and fresh, but the majority require a long storage period to increase germination rates,”says Zitobile. “One of the interesting facts about restios is that there are separate male and female plants. The females produce seeds while the males produce pollen. Restios are wind-pollinated and they don’t hybridise. They are also propagated through division, not cuttings. We do however have to take specimens from the roots of the restios from which we have collected the seeds as the taxonomists at the herbarium require underground parts for identification purposes.”
Zoleka Maphanga, who is a seed processing co-ordinator at the Millennium Seed Bank at Kirstenbosch, added: “We have to choose sunny, windless days for seed collection and we check the seeds with a small magnifying glass to ensure that they are viable and not damaged by insects. We also note whether the seeds are collected from the plant or the ground. The seed is banked in specially designed seed banks at low temperatures to preserve them for a long time. Half the seed collected is stored for us at the Millennium Seed Bank in Britain and the other half is stored in a seed bank in South Africa. We try to collect more than a 1000 seeds of a species at a time, but only 10% of the seeds available on a single plant or plant population in order not to impact on the seed available in habitat.”
In answer to the question as to whether new species of fynbos are still being found, we were told that a new species comes to light on the Cape Peninsula every one to two years.
We had set off in balmy weather from the gardens far below but by now we had pulled on our wind cheaters and jerseys. One certainly needs to be well prepared for all kinds of weather when hiking up Table Mountain. Bundu bashing through high stands of proteas and restios, Anthony took us on a side excursion into a cleft in the mountain where the mist filtering through the ancient trees of the remnant indigenous forest lent an ‘ancient earth’ kind of atmosphere.
“Below us is one of the longest sandstone caves in the world, measuring 4.5km. It includes the well known Wynberg Cave. On the other side of this crest the cliff-face falls steeply into Orange Kloof. This part of the mountain is, very slowly, sheering off from the main part of Table Mountain , causing deep ‘ cracks’ in which caves develop. The process is known as mass movement,” explained Anthony, an ardent speleologist. “These clefts and caves are a refuge for a number of ancient Gondwana animal species. A rare white Peripatus, Peripatopsis alba, is only found in these caves. A researcher found nine new animal species in Wynberg Cave in one year. These caves are very dangerous and I recommend that people avoid them or contact the Cape Peninsula Spelaeological Society if they want to explore the caves.” (http://cpss.caving.org.za/) Peripatus is a genus of Onychophora. It is an invertebrate which gives birth to live young rather than laying eggs. It is said to be a living fossil because it has remained unchanged for approximately 570 million years.
On our return to Kirstenbosch, Louise prepared a seed tray while Zitobile and Ntsindiso got the smoker going. Back in the 1990s Hannes de Lange discovered that smoke is required for restio and many other fynbos seeds to germinate. A fire using old branches of fynbos plants is made in a 44 gallon drum which has a pipe leading from it to a structure covered by thick plastic sheeting, under which the seed trays are placed. A compressor connected to the drum is used to pump the smoke from the drum to the tent. Within seconds thick smoke billows out from under the sheeting. The seeds are exposed to the spicy smoke for two hours and within a few days or weeks (depending on the species) they germinate freely. All Restionaceae and Erica seeds are smoked. Smoking also works with other species such as the daisy family. Once the seeds have been smoked, the trays are placed under cover in the nursery and watered regularly.
“The question of the time span required for germination by fire of fynbos in the wild is controversial. Some researchers say 8-10 years, others 15 years. It depends on where you are. The fynbos in the dry inland mountain habitats need much longer gaps between burns than the moister coastal fynbos. A lot of the research regarding fires and fynbos was done in the Jonkershoek where it is very wet. In dry areas huge damage is done by fires occurring too frequently. The ornamental grasses that grow after a fire are short lived and soon dry out. Proteas and other woody plants such as ericas growing in the previously burnt area often only get to be 4-5 years old before fires sweep through the area again. The young plants together with the woody species are destroyed as, not having reached maturity they have not been able to set enough seed,” explains Anthony.
Cuttings receive “under floor” heating and regular moistening from mist spray, a two-second spray every ten minutes to prevent the cuttings drying out. The medium in which the fynbos is grown is a mixture of rotted pine bark and polystyrene pellets for aeration and has no nutrients. Rooted fynbos plants are grown in a mixture of river sand and composted bark. “This is easier to keep sterile than loam which has lots of pathogens. We have to be careful with the quality of the sand. We used to get it from the Berg River, but it is too fine and also contains too many alien seeds. We now get it from Consul on the Cape Flats. There are different grades of sand – we have to be careful to get sand with the correct Ph level. It must be acidic. As it is, only about 5% of seed taken from a protea head will germinate,” explained Louise.
A new heat pump system is currently being installed in the nursery which will run warm water under the cutting trays providing the required heat for accelerating the rooting of cuttings. The new system will translate into a 70% saving in electricity costs, which is considerable. This saving is also available for homeowners and businesses wishing to save on electricity costs.
In the covered nurseries young plants at various heights and stages of growth create a pleasing display. From the seed trays the tiny saplings are planted into small plugs, helping to save water and a great deal of space. They are nursed from the smallest containers into progressively larger ones and are monitored daily. Some of these plants have to be hand pollinated to make sure that they do not hybridise. Plants are grown for the gardens as well as for sale at the annual Kirstenbosch Plant Sale and the retail nursery near the tearoom.
Before heading off to the Millennium Seed Bank offices, Anthony proudly showed us his Erica collection which includes species that are extinct in the wild. Seeds are not collected from the plants in this collection in order to prevent hybridisation. The most prized species in the collection is Erica verticillata which became extinct in the wild by the 1950s. It was rediscovered in various Botanical Gardens and private collections around the world and brought back to Kirstenbosch. It has since been re-established in three natural habitats around Cape Town. (See http://www.plantzafrica.com/ for the full story)
Our final stop was at the Millennium Seed Bank offices where Zoleka explained the work that she does. Here thousands of seeds are sorted by hand and by the time-saving air-blowing machine, the aspirator. They are labelled together with details about their habitat and place of origin similar to the information collected for the Kirstenbosch Gardens database and then the seed is stored in the cold room until sent to England. Seeds are flown over to Kew’s Millennium Seed Bank based at Wakehurst in the UK about four times a year.
At Wakehurst over a billion saved seeds representing over 10% of the planet’s wild plant species from over 130 countries are stored at temperatures of between -20 and -40 degrees C. The goal is to have safely stored 25% of the world’s most endangered and useful seeds by 2020. Duplicate seeds are kept in the country of origin. Several species in the bank are already extinct in wild. Kirstenbosch has an agreement with the blood bank in Pretoria for the storage of half of the duplicates from Southern Africa. Anthony would like to establish a permanent seed bank at Kirstenbosch, but to create such a facility is very expensive. Most of the processing of South African plant species is done at Kirstenbosch.
Sarah-Leigh Hutchinson of the Cape Millennium Seed Bank, and colleague of Zoleka, showed us some of the pressed plants and explained that at least three specimens of each plant have to be pressed. These pressed specimens are sent along with their seed to the Wakehurst and also identified and kept as a herbarium record in the Compton Herbarium at Kirstenbosch and the National Herbarium in Pretoria.
In reading up about the Millennium Seed Project on the Internet I was delighted by a story on video on http://www.kew.org/visit-wakehurst/index.htm. In 1803 a Dutch merchant sailed back to Holland with seeds from a now critically endangered species of protea growing in the South Western Cape, hoping to cultivate them in his home country. At the time the British and Dutch were at war and his ship was intercepted by British privateer. The merchant and the seed were incarcerated in the Tower of London where the seeds were unearthed last year. Kew now has a healthy young protea bush grown from them!
The horticulturists from Kirstenbosch collect seeds from threatened plant species and from threatened habitats from as far afield as Namibia and Angola. Carmel Mbizvo, Deputy Director General of Research Policy and Knowledge at SANBI, who accompanied us on the excursion, has recently signed Phase 2 of the Millennium Seed Bank Project which focuses on the conservation in South Africa of the habitats of threatened species and the education of the communities in these areas. “When the members of the community know that there is only one of the species left they will want to care for it. For example, North Pine near Kraaifontein on the Cape Flats hosts the last wild growing specimen of the critically endangered Kraaifontein Spiderhead. This species was once abundant in the area, but its habitat has been destroyed by development. The North Pine site has been designated for a warehouse supplying a well-known shopping centre, so the last remaining plant has been surrounded by a fence 50m in diameter, which is unsustainable for a reserve,” says Anthony. Keeping endangered plants in their natural habitat is the best way to preserve these species because many fynbos plants are very difficult to grow at Kirstenbosch, which is much wetter and more suitable for growing trees than fynbos. The result is that many fynbos species get fungal and other infections at Kirstenbosch.
The next best option is to collect and preserve them in seed banks. Many thousands of seeds can be stored in a relatively small space and at less of a cost than living plants in pots. “The Cape lowland is the most threatened habitat in South Africa and we will lose many species in the next few decades if we do not try to conserve them. The Millennium Seed Bank is therefore the best option for preventing loss of species,” explains Anthony.
Horticulturalists from Kirstenbosch have been also been restoring Erica verticillata at Rondevlei, Kenilworth Racecourse Conservation Area and Tokai. This species has been listed as extinct. Anthony continues: “The species has to be planted, to have produced seed, survived three fires, and regenerated three times without intervention before it may be re-classified as not extinct in the wild and delisted to a lower risk category. When restoring an area, emphasis must be given to the biodiversity of the whole eco-system. In Kenilworth the ericas are flowering, but not setting seed because there are no pollinators in the area. Kenilworth conservation staff are trying to encourage sunbirds to the area. The re-planting in Tokai (an area where thousands of plantation pine trees were harvested) has seen some successful restoration of threatened species lost from the area. Some of the restored species have been mapped so that we can monitor successes and failures. When we have failures, we learn and we go back to the drawing board!”
“Our stock beds for threatened species at Kirstenbosch receives no irrigation and faces South East – towards Muizenberg,” adds Louise. “There they are exposed to cooler south-east winds and therefore cooler temperatures in summer. We do not irrigate these beds and therefore diseases that are spread by water are excluded. We have a population of endangered species that are kept out of the public eye. Of the 120 species, 80 are on the Red Data list, the majority of which are Proteaceae.” Speaking of her work, Louise says that she really enjoys the fact that each day is different. “I have such a broad mandate and it is important work, which can be very daunting.”
Anthony took over the management of the nursery in 2000, reluctantly at first as he prefers growing plants to desk work. He therefore also manages the Erica collection and garden section. “The gardens can be developed in many different ways. Some of my colleagues prefer pure display horticulture where they use textures and colour to great effect in their sections. Others prefer to plant according to the regions that the plants come from such as in the Conservatory. When deciding upon a planting theme, one can plant sweeps of colour in a garden for dramatic effect or place plants together that have the same pollination systems. One could have beds for bird pollinated plants and others for bee-pollinated plants, for example. Louise and I have chosen to plant according to a phyto-geographic system as presented in the book Cape Plants by Peter Goldblatt and John Manning. (GOLDBLATT, P. and MANNING, J. 2000. Cape Plants. A conspectus of the Cape flora of South Africa. Strelitzia 9) This means we plant Ericas or Proteas in garden beds dedicated to a region such as the southern Cape or the drier areas north west of Cape Town. We plant the most important species representing the region along with their companion plants representing other fynbos families. The aim is that the region represented in the garden bed must show or remind the visitor of the natural area. So the North West bed must remind people of the Cedarberg. Forms of Erica and other fynbos also differ from area to area. For example the Erica cerinthoides here on Table Mountain is quite different in size and form when compared with the same species in other regions. This diversity of species and fynbos from region to region advertises the rich complexity of our fynbos.”
It was a most interesting and informative excursion. Having made my farewells, and exhausted by a huge amount of new information my aging brain had now to process, I sank onto a bench in the shade and contemplated with gratitude the beauty of the gardens before me, created by the dedicated people in whose company I had spent the morning and their many hardworking colleagues. My appreciation of Kirstenbosch has indeed been deepened by my peek into what goes on at Kirstenbosch behind the flowerbeds!
Copyright Vivienne von der Heyden
With thanks to Anthony Hitchcock and Louise Nurrish of Kirstenbosch for the opportunity to join them on the field trip and for their careful editing and additional input.