Kirstenbosch Hothouse

Beez Neez now Chy Whella
Big Bear and Pepe Millard
Mon 13 Jan 2020 23:57
Kirstenbosch Hothouse
 
 
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Bimbling into the huge Hothouse at Kirstenbosch was a joy of new ‘stuff’ to us, mostly from Namibia.
 
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We turned right, found ourselves in a ‘little outside bit’ and took in some lovely plants.....
 
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Another collection of Bonsai Trees. My personal favourite Acer, although I do love the ones with dark purple, deeply cut leaves best of all. This one is Chinese or Trident Maple (Acer buergerianum) and he is 70 years old.
 
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A False Olive (Buddleja saligna) aged 50 years and a Wild Olive (Olea europaea subsp. africana) aged 95 years.
 
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Loved the holes and hollows in this chaps trunk. He is a Chinese or Laccbark Elm (Ulmus parvifolia) aged 25 years.
 
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A fine Swamp or Bald Cypress (Taxodium distichum) aged 25 years. Bear was busy reading an interesting story.
 
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Saved from extinction: Erica verticillata once grew in the area between Rondebosch and Rondeviei. Cuttings and seeds had been collected and plants cultivated at Kirstenbosch and in other botanic gardens, but by the 1960s all the Kirstenbosch Erica verticillata plants had died. When staff went to collect fresh seed and cuttings from the wild plants, they searched all over what was left of its habitat, but no plants were found. Erica verticillata was thought to be extinct. Luckily plants had survived in other gardens and to date Kirstenbosch staff have tracked down eight different individual plants. Today, this species survives in cultivation at Kirstenbosch, and in many other botanic and private gardens all over the world, and plants have been successfully re-introduced to reserves on the Cape Flats.
The last recorded collection of a wild plant was in 1908.
 
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In 1990, a plant was found in an underdeveloped part of Kirstenbosch, where ericas had been planted in the 1920 and ‘30s.
The Heather Society of Britain found and returned three plants: from a Southampton garden centre, the private collection of Violet Gray, and Tresco Abbey Garden (one of our favourite places).
The Royal Botanic Garden, Kew sent one in 1984 that proved to be a hybrid, and another in 2006 that was originally sent to Kew from Fernkloof Botanic Garden in Hermanus.
Protea Park, Pretoria: a plant growing here was recognised from herbarium sheets. Cuttings were sent to Kirstenbosch in 1984.
Bundersgarten (Belvedere Palace) in Vienna has been growing two forms since the 1790s, one true species, one hybrid. Cuttings were returned to South Africa in 2001.
The Heather Society of America found and returned a plant from a Californian nursery in 2006.
From these eight Erica verticillata plants, thousands more have been grown from cuttings. We were too late to prevent this species from dying out in nature, but we can make sure that it survives by growing it in our gardens and looking after the seeds. What a lovely story and so many societies and gardeners across the world got involved to make this a success for the future.
 
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In the far corner we were drawn to look at what at first glance looked like bits of tree stumps. We touched as the information board suggested and found them cold to the touch and very stone-like indeed. Trees of Stone: These are fossil tree stumps. They were living trees about 240 million years ago, when South Africa was part of the ancient continent of Gondwana. Today fossils like these are found in the eastern Free State in the Senekal and Harrismith districts. When living they were trees that looked similar to the Monkey Puzzle and Norfolk Island Pine (Araucaria spp.) found in the South Pacific, Australia and New Zealand today. There are no more of their kind native to Africa alive today. This ancient plant group went extinct in Africa but survived in other parts of Gondwana.
Fossil wood can tell us about the climate long ago. The annual growth rings of these fossil trees indicate that the climate was strongly seasonal, but wet and warm enough for forests to grow.
How do trees turn to stone?: A tree trunk may be swept away by a flood and then become covered in mud or sand. This cuts out air (oxygen), which stops the normal process of decay by fungii and bacteria. Gradually the sand layers build up and minerals enter the tree trunk, slowly replacing the organic material, particle by particle. In this way over a long time the organic wood becomes turned into mineral stone (petrified). I think I need a rub down with the Evening Post....
 
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Back inside the hothouse we went anti-clockwise and chose some favourites from the first collection.
 
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Orchidaceae (Eulophia ensata), and two Amaryllidaceae (Haemanthus humilis).
 
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Lovely Flame Lilies.
 
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At the end of the path was a stout fellow called Cobas from the Namib (Cyphostemma curroii).
 
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Then we saw, in the far corner what looked like ‘past it’s sell by date’ only to discover the most amazing plant we have ever seen. Welwitschia mirabilis is a very unusual plant from the Namib Desert. There is no other plant like it. It is made up of just two leaves, a stem base and roots. It does not fit neatly into any plant group because it bears cones like a cone-bearing plant (gynosperm), yet has some characteristics of flowering-plants (angiosperms), and has no close relatives. It is found growing wild only in the Namib, from Swakopmund in northern Namibia in south-west Angola. Welwitschias produce only two strap-shaped leaves that keep growing throughout the plant’s life, and are never shed. They become torn, shredded and tattered with age. Some plants are estimated to be between 500 and 2000 years old.
 
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Cones are produced on both male and female plants (dioecious), both produce cones, but, unlike other cone-bearing plants, Welwitschia cones contain modified flower-like structures that are more like those found in flowering plants. The ‘flowers’ produce nectar, which attracts small insects like flies and wasps, which pollinate them.
The stem of a mature Welwitschia mirabilis is low, sturdy, woody and hollowed out, like an ice-cream cone. They have this strange shape because of their unique growth habit. The growing point at the tip of their stems stops growing when they are still young. The stem margin continues to grow out sideways, with no upward growth from the centre. Most of them grow about half a metre tall, although the largest wild plant is nearly 3 m high and about 9 m wide.

Welwitschia live in an extreme desert environment, yet has few adaptations to desert life that most desert plants have. In many ways this strange plant is more like the kind of plant you would expect to find in a moist tropical climate rather than a desert. Welwitschia does not store water in its stems or leaves. Desert plants have no leaves, small leaves or fleshy leaves, but Welwitschia has large, broad leaves.

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Welwitschia has many stomata in its leaves, more than most desert plants do, and they are found on the upper and lower surfaces. Stomata are pores in the leaf surface for gas exchange, and moisture is lost during this process – the more stomata, the more water is lost. It was thought that Welwitschia could absorb fog and water vapour through the stomata, but recent studies show that it cannot. Why it has so many stomata is a puzzle.
Welwitschia has a very long taproot, which can reach underground water. The broad leaves reflect much of the sun’s heat and light so that the leaves don’t overheat. The leaves also shade the soil around the stem, keeping the rots cooler and conserving any moisture in the soil.
To grow Welwitschia we have brought the desert to Kirstenbosch. This bed is filled with well-drained, desert sand, and heating cables keep it warm all year round. The bed is deep to allow Welwitschia’s long tap root to develop. We sowed the seeds directly in the bed, because the long tap root makes them difficult to transplant. We treated the seedlings with a fungal inoculant and water once a week in summer and once every three weeks in winter.
The oldest Welwitschia in this house were sown in November 2010. Although some produced their first cones when they were only 13 months old, it takes many years for them to develop their strange, woody, hollowed-out-cone-like stems. After reading the information boards we believe this is the most incredible plant we have ever met....
 
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In the far corner we saw the most marvellous, showy cactus – Apocynaceae (Hoodia gordonii).
 
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 Upstairs we saw far too many plants to name......
 
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......but a little chap in the corner had the reddest flowers, perhaps ever.
 
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The chap in the middle is Vitaceae (Cyphostemma bainesii) and the little stumpy chaps are Asteraceae (Kleinia stapliiformis).
 
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The Quiver Tree (Aloidendron dichotomum): These species earned its name, not because it trembles or quivers in the wind, but because in the old days Bushmen hunters used branches from this tree to make quivers to carry their arrows. They hollowed out the branch and covered the open end with a piece of leather.
The Quiver Tree is Red Listed as Vulnerable, it faces a high risk of extinction in the wild in the near future. Climate change is the Quiver Tree’s greatest threat: as the climate warms and dries the plants in existing populations are not coping with the change and are dying. It was hoped that this species would move into more suitable areas south and east of its current range but no new populations have been found. Scientists predict that nearly three quarters of the population will disappear in the next 100 years if no new areas are colonised.
Sugarbirds and sunbirds feed on the nectar in the flowers. And in the wild, communal weavers build their huge nests (up to 500 birds), in the branches of the trees, where the young are safe from jackals and other predators.
The Quiver Tree grows wild in Namaqualand and Bushmanland, from Niewoudtville eastwards to Olifantsfontein in the Northern Cape, and northwards to Brandberg in Namibia. It grows on north-facing rocky slopes in the southern part of its range and on slopes and sandy flats in the central and northern parts.
 
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Other than making good quivers the flowers can be eaten – they are said to taste like asparagus. The trunks yields a kind of gum. The trunks of large dead trees are hollowed out and used as natural fridges to store water, meat and vegetables – the fibrous trunk cools the air as it passes through.
The Quiver Tree is a beautiful, sculptural plant that would be an asset in any garden (I love the higgledy branches). It needs a sunny position in very well-drained soil. A hot sunny rockery is best. It will also grow well in large containers. Care must be taken not to overwater as it will rot if the soil is poorly drained or constantly wet. Propagate from seed sown in autumn or truncheon cuttings dried out for at least 3 weeks before planting. One for my list and a good excuse for typing out all the info. So throughout the day bimbling about in the Garden, I / we have gone from living in an apartment to buying a house that now needs a conservatory, greenhouse, potting shed and many big containers......
 
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Loved the hole at the bottom of this Candle Bush.
 
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Our final chap was rather lovely, no not Bear......the leaves looked as if someone had glued them on to the stem as an afterthought. Cyptostemma currorii. What an incredible hothouse.
 
 
ALL IN ALL SOME WONDERFUL ODDITIES
                     REALLY WEIRD AND INTERESTING