Silver tree | |
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A young silvertree at Kirstenbosch Botanical Gardens, Cape Town | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Proteales |
Family: | Proteaceae |
Genus: | Leucadendron |
Species: | L. argenteum |
Binomial name | |
Leucadendron argenteum | |
Map of the extant population of silvertrees in the Cape Peninsula | |
Synonyms [2] | |
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Leucadendron argenteum (silver tree, silver leaf tree, Afrikaans : Witteboom, or Afrikaans : Silwerboom) is an endangered plant species in the family Proteaceae, which is endemic to a small area of the Cape Peninsula, South Africa. Most grow in and around the city of Cape Town, but outlying (perhaps introduced) populations exist near Somerset West (Silwerboomkloof), Paarl and Stellenbosch. It is a protected tree in South Africa. [3]
The silvertree is a striking evergreen tree, growing 5–7 m tall (sometimes up to 16 m). It is erect and well-proportioned with a thick, straight trunk and grey bark. The soft, silky leaves are shiny silver, lanceolate, 8–15 cm long and 2 cm broad, with their distinct silvery sheen produced by dense velvety hairs. The wind-pollinated flowers are produced in dense globose inflorescences 4–5 cm diameter, and give off a pleasant scent. Like all Leucadendrons, this tree is dioecious, with separate male and female plants. The fruit is a heavy woody cone, containing numerous seeds; each seed is a small nut with a silky-haired helicopter-like parachute, enabling it to disperse by wind. After germination it pushes up two green, bare and leathery cotyledons.
This enormous silver Protea is naturally confined to a tiny area in and around the city of Cape Town. Its main population grows on the slopes of Table Mountain, notably the Lion's Head area, above Rhodes Memorial and the mountain slopes above Kirstenbosch National Botanical Garden.
In addition, there are three tiny outlying populations nearby, in Stellenbosch, Somerset West and Paarl (it has not yet been established for certain whether these are natural outliers, or were planted here in early Cape history). The Somerset West population is located within a natural heritage site called Silvertree Gorge, in the Spanish Farm suburb.
Historically, the silvertree was more widespread on Table Mountain, covering much of its slopes in shimmering silver forests. However, early demand for timber led to much of these forests being felled and now the silvertree is a rare and endangered species. [4]
Table Mountain is perhaps the only place where these trees grow naturally, as the populations near Stellenbosch and Paarl (though conceivably natural) may have been introduced from Table Mountain.
In the face of urban development, inappropriate fire management, and invasive alien trees such as pines and gums, silvertrees have been driven from about 74% of their natural range. [5] Mortality of these short-lived trees is negligible after a burn, but then increases to about 5% per annum. During a longer term absence of burns however, sudden die-offs may occur, even in a matter of hours. This is believed to be the combined result of (warm) berg winds and diseased roots which are weakened by Phytophthora root rot which inhibits their water absorption.
An estimated 40 to 50 percent of the extant native population burned in the fire of 26 to 27 January 2006. [6] As recruitment of seedlings only occurs naturally after fire, this was a necessary stage in the life-cycle of this Fynbos species, and the population has recovered totally.
A major deterrent to propagation of the silver leaf tree is its short life span, as most don't live more than 20 years. This doesn't affect their conservation however, as fires rejuvenate populations on average every 15–20 years by killing the surviving adults and triggering the release of the canopy seed bank (in the cones), and germination of the soil seed bank. Seeds remain viable for at least 80 years. Juveniles take 5–7 years to flower and set seed, whereafter the populations are ready to burn again.
"[S]tylized twigs of the silver tree" [ sic ] appear in the arms of the South Peninsula Municipality of South Africa. [7]
The Cape Peninsula is a generally mountainous peninsula that juts out into the Atlantic Ocean at the south-western extremity of the African continent. At the southern end of the peninsula are Cape Point and the Cape of Good Hope. On the northern end is Table Mountain, overlooking Table Bay and the City Bowl of Cape Town, South Africa. The peninsula is 52 km long from Mouille point in the north to Cape Point in the south. The Peninsula has been an island on and off for the past 5 million years, as sea levels fell and rose with the ice age and interglacial global warming cycles of, particularly, the Pleistocene. The last time that the Peninsula was an island was about 1.5 million years ago. Soon afterwards it was joined to the mainland by the emergence from the sea of the sandy area now known as the Cape Flats. The towns and villages of the Cape Peninsula and Cape Flats, and the undeveloped land of the rest of the peninsula now form part of the City of Cape Town metropolitan municipality. The Cape Peninsula is bounded to the north by Table Bay, to the west by the open Atlantic Ocean, and to the east by False Bay in the south and the Cape Flats in the north.
Table Mountain National Park, previously known as the Cape Peninsula National Park, is a national park in Cape Town, South Africa, proclaimed on 29 May 1998, for the purpose of protecting the natural environment of the Table Mountain Chain, and in particular the rare fynbos vegetation. The park is managed by South African National Parks. The property is included as part of the UNESCO Cape Floral Region World Heritage Site.
Leucadendron is a genus of about 80 species of flowering plants in the family Proteaceae, endemic to the Cape Provinces and KwaZulu-Natal in South Africa, where they are a prominent part of the fynbos ecoregion and vegetation type.
Helderberg refers to a planning district of the City of Cape Town metropolitan municipality, the mountain after which it is named, a wine-producing area in the Western Cape province of South Africa, or a small census area in Somerset West.
Newlands Forest is a conservancy area on the eastern slopes of Table Mountain, beside the suburb of Newlands, Cape Town, South Africa. It is owned and maintained by the Table Mountain National Parks Board, along with the City Parks Department of Cape Town, and includes a Fire Station, Nursery and Reservoir.
Leucospermum conocarpodendron is the largest species of the genus Leucospermum, reaching almost tree-like proportions of 5–6 m (16–20 ft) high with a firm trunk that is covered in a thick layer of cork that protects it from most fires. It has greyish or green narrow or broad inverted egg-shaped leaves with three to ten teeth near the tip and large yellow flowerheads, with firm, bent, yellow styles that stick far beyond the rest of the flower and give the impression of a pincushion. It is commonly known as the tree pincushion in English or goudsboom in Afrikaans. They naturally occur near Cape Town, South Africa.
Peninsula Granite Fynbos is an endangered Fynbos vegetation type which is endemic to the city of Cape Town and occurs nowhere else. It is a unique type of tall, dense and diverse scrubland, scattered with trees. It can be found all along the belt of granite that encircles Table Mountain.
Cape Winelands Shale Fynbos is a vegetation type that naturally occurs in the Cape Winelands of the Western Cape, South Africa.
Southern Afrotemperate Forest is a kind of tall, shady, multilayered indigenous South African forest. This is the main forest-type in the south-western part of South Africa, naturally extending from the Cape Peninsula in the west, as far as Port Elizabeth in the east. In this range, it usually occurs in small forest pockets, surrounded by fynbos vegetation.
De Hel Nature Area is a 21.3-hectare (53-acre) nature reserve protecting a river valley and indigenous forest on the lower eastern slopes of Table Mountain, Cape Town, South Africa.
Silwerboomkloof Natural Heritage Site is a small, protected valley (“kloof”), near the Helderberg Nature Reserve, in Somerset West, South Africa.
Die Oog Conservation Area is a tiny 1.2-hectare (3.0-acre) nature reserve within the city of Cape Town, South Africa.
Cecilia is a section of the Table Mountain National Park on the lower eastern slopes of Table Mountain in Cape Town, located just to the south of Kirstenbosch National Botanical Garden. It was previously used for commercial logging and known as Cecilia Forest or Cecilia Plantation, but has now been given protected status and integrated into the National Park.
Tokai Park, previously known as "Tokai Forest", is a small wing, about 600 ha, of the greater Table Mountain National Park in Cape Town, South Africa. Tokai Park is made up of two sections: upper and lower Tokai Park. Lower Tokai Park is flat, and characterized by the threatened Cape Flats Sand Fynbos. Upper Tokai Park is on the slopes of Constantiaberg Mountain, and consists of conservation area as well as the Tokai Arboretum. Upper Tokai Park is characterized by Peninsula Granite Fynbos, Peninsula Sandstone Fynbos and Afromontane Forest and noted for its diversity.
Leucadendron coniferum, also known at the dune conebush, is an evergreen, dioecious shrub or small tree of up to 4 m (13 ft) high, that has been assigned to the family Proteaceae. It has a whorl of conspicuous yellow leaves subtending the flowerheads. The flowers can be found in August and September. It grows in sandy soils near the coast of the Western Cape province of South Africa.
Leucospermum cuneiforme is an upright evergreen shrub with many pustules growing on the lower branches, wedge-shaped leaves, and oval, initially yellow flower heads that later turn orange, with long styles sticking far beyond the perianths, jointly giving the impression of a pincushion. It is called wart-stemmed pincushion in English and luisiesbos (lice-bush) in Afrikaans. The species is common in the southern mountains of South Africa.
Leucospermum vestitum is an evergreen, upright to more or less spreading shrub of up to 2½ m (9 ft) high and wide from the family Proteaceae. It has greyish, seated, oblong, 2–3 inch long leaves with two to four teeth near the tip and large, showy two-toned flower heads that are bright orange at first by and age to brilliant crimson. From the center of the perianth emerge long styles, higher up bending towards the center of the head, that jointly give the impression of a pincushion. It is called silky-haired pincushion in English and bergluisie in Afrikaans. It can be found in the Western Cape province of South Africa, and flowers from July until January, peaking October and November.
Leucadendron spissifolium subsp. fragrans, the fragrant spear-leaf conebush, is a flower-bearing shrub belonging to the genus Leucadendron. The plant is native to the Western Cape and occurs in the Langeberg and Outeniqua Mountains from Gysmanshoek to the Woodville Forest Reserve, as well as the Swartberg and Kammanassie Mountains. It forms part of the fynbos.
Leucadendron spissifolium subsp. spissifolium, the common spear-leaf conebush, is a flower-bearing shrub belonging to the genus Leucadendron and forms part of the fynbos. The plant is native to the Western Cape where it occurs on the Gifberg and from the Cederberg to the Cape Peninsula and Kogelberg to Kampscheberg in the Langeberg.
Leucadendron macowanii, the acacia-leaf conebush, is a flower-bearing shrub that belongs to the genus Leucadendron and forms part of the fynbos. The plant is native to the Western Cape, South Africa.