Leucadendron Argenteum
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''Leucadendron argenteum'' (silver tree, silver leaf tree, , or ) is an endangered plant species in the family
Proteaceae The Proteaceae form a family (biology), family of flowering plants predominantly distributed in the Southern Hemisphere. The family comprises 83 genus, genera with about 1,660 known species. Australia and South Africa have the greatest concentr ...
, which is
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to a small area of the
Cape Peninsula The Cape Peninsula () of South Africa 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 ...
,
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
. Most grow in and around the city of
Cape Town Cape Town is the legislature, legislative capital city, capital of South Africa. It is the country's oldest city and the seat of the Parliament of South Africa. Cape Town is the country's List of municipalities in South Africa, second-largest ...
, but outlying (perhaps introduced) populations exist near
Somerset West Somerset West () is a town in the Western Cape, South Africa. Organisationally and administratively it is included in the City of Cape Town metropolitan municipality (South Africa), metropolitan municipality Eastern Suburbs zone (formerly called ...
( Silwerboomkloof),
Paarl Paarl (; ; derived from ''parel'', meaning "pearl" in Dutch) is a city with 294,457 inhabitants in the Western Cape province of South Africa. It is the largest city in the Boland, Western Cape, Cape Winelands. Due to the growth of the Mbekweni ...
and
Stellenbosch Stellenbosch (; )A Universal Pronouncing Gazetteer.
Thomas Baldwin ...
. It is a protected tree in South Africa.


Appearance

The silvertree is a striking
evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
, 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 A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...
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
flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...
s are produced in dense pink, globose
inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...
s 4–5 cm diameter, and give off a pleasant scent. Like all Leucadendrons, this tree is
dioecious Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...
, with separate male and female plants. The
fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
is a heavy woody cone, containing numerous
seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...
s; 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 A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow", gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...
.


Distribution

This enormous silver
Protea ''Protea'' () is a genus of South African flowering plants, also called sugarbushes (Afrikaans: ''suikerbos''). It is the type genus of the Proteaceae family. About 92% of the species occur only in the Cape Floristic Region, a narrow belt of mo ...
is naturally confined to a tiny area in and around the city of
Cape Town Cape Town is the legislature, legislative capital city, capital of South Africa. It is the country's oldest city and the seat of the Parliament of South Africa. Cape Town is the country's List of municipalities in South Africa, second-largest ...
. Its main population grows on the slopes of
Table Mountain Table Mountain (; ) is a flat-topped mountain forming a prominent landmark overlooking the city of Cape Town in South Africa. It is a significant tourist attraction, with many visitors using the Table Mountain Aerial Cableway, cableway or hik ...
, notably the Lion's Head area, above Rhodes Memorial and the mountain slopes above
Kirstenbosch National Botanical Garden Kirstenbosch is a botanical garden nestled at the eastern foot of Table Mountain in Cape Town. The garden is one of 10 National Botanical Gardens covering five of South Africa's six different biomes and administered by the South African Natio ...
. In addition, there are three tiny outlying populations nearby, in
Stellenbosch Stellenbosch (; )A Universal Pronouncing Gazetteer.
Thomas Baldwin ...
,
Somerset West Somerset West () is a town in the Western Cape, South Africa. Organisationally and administratively it is included in the City of Cape Town metropolitan municipality (South Africa), metropolitan municipality Eastern Suburbs zone (formerly called ...
and
Paarl Paarl (; ; derived from ''parel'', meaning "pearl" in Dutch) is a city with 294,457 inhabitants in the Western Cape province of South Africa. It is the largest city in the Boland, Western Cape, Cape Winelands. Due to the growth of the Mbekweni ...
(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 Table Mountain (; ) is a flat-topped mountain forming a prominent landmark overlooking the city of Cape Town in South Africa. It is a significant tourist attraction, with many visitors using the Table Mountain Aerial Cableway, cableway or hik ...
, 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.


Status and conservation

Table Mountain Table Mountain (; ) is a flat-topped mountain forming a prominent landmark overlooking the city of Cape Town in South Africa. It is a significant tourist attraction, with many visitors using the Table Mountain Aerial Cableway, cableway or hik ...
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 A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as ...
and
gums The gums or gingiva (: gingivae) consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health. Structure The gums are part of the soft tissue lining of the ...
, silvertrees have been driven from about 74% of their natural range. 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 ''Phytophthora'' (from Greek (''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a genus of plant-damaging oomycetes (water molds), whose member species cause economic losses on crops worldwide, as well as environmental dam ...
'' 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. As recruitment of seedlings only occurs naturally after fire, this was a necessary stage in the life-cycle of this
Fynbos Fynbos (; , ) is a small belt of natural shrubland or heathland vegetation located in the Western Cape and Eastern Cape provinces of South Africa. The area is predominantly coastal and mountainous, with a Mediterranean climate. The 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 The soil seed bank is the natural storage of seeds, often dormant, within the soil of most ecosystems. The study of soil seed banks started in 1859 when Charles Darwin observed the emergence of seedlings using soil samples from the bottom of a lak ...
. 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.


Heraldry

"'' ylized twigs of the silver tree''" appear in the arms of the South Peninsula Municipality of South Africa.


Pictures

File:Leucadendron argenteum - Silvertree Forest - Table Mountain 4.JPG, Silvertrees were driven to near extinction when their natural habitat was cleared for commercial pine plantations. File:Leucadendron argenteum - Silvertree Forest - Table Mountain 3.JPG, Silvertrees grow only in and around
Cape Town Cape Town is the legislature, legislative capital city, capital of South Africa. It is the country's oldest city and the seat of the Parliament of South Africa. Cape Town is the country's List of municipalities in South Africa, second-largest ...
, particularly on
Table Mountain Table Mountain (; ) is a flat-topped mountain forming a prominent landmark overlooking the city of Cape Town in South Africa. It is a significant tourist attraction, with many visitors using the Table Mountain Aerial Cableway, cableway or hik ...
. File:Leucadendron argenteum - Silvertree - Rhodes memorial.JPG, A large silvertree near Rhodes Memorial File:Leucadendron argenteum - Silvertree Forest regrowth - Table Mountain 3.JPG, A young stand of silvertrees on Devil's Peak,
Table Mountain Table Mountain (; ) is a flat-topped mountain forming a prominent landmark overlooking the city of Cape Town in South Africa. It is a significant tourist attraction, with many visitors using the Table Mountain Aerial Cableway, cableway or hik ...
. File:Leucadendron argenteum - Silvertree Forest - Devils Peak.JPG, A silvertree forest on the lower slopes of Devil's Peak File:Leucadendron argenteum - Silvertree Forest - Table Mountain regrowth.JPG, Partial removal of the invasive
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...
plantations allowed silvertree forests to gradually return. File:Leucadendron argenteum - new growth detail.JPG, Silver tree leaves are soft and silky. File:Leucadendron argenteum 4.jpg, New growth detail File:Leucadendron argenteum 5.jpg, The silver leaf colour is due to their soft velvety hair File:Leucadendron argenteum - Silvertree - foliage 6.JPG File:Female cone Leucodendron argenteum.jpg, Heavy cone of a female tree, which eventually opens to release the small, round nuts File:Starr 000913-9002 Leucadendron argenteum.jpg, Cone, seeds, leaf and juvenile plant


See also

* List of Southern African indigenous trees * Peninsula Granite Fynbos * Silwerboomkloof * Rhodes Memorial * Newlands Forest


References


External links


''Leucadendron argenteum'' PlantZAfrica.com
* ttp://www.proteaatlas.org.za/cpldarge.htm ''Leucadendron argenteum'' in the Protea Atlas {{Taxonbar, from=Q3644294 argenteum Endemic flora of the Cape Provinces Natural history of Cape Town Fynbos Trees of South Africa Endangered flora of Africa Protected trees of South Africa Trees of Mediterranean climate Garden plants of Southern Africa Ornamental trees