Leucadendron argenteum

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Silver tree
Leucadendron argenteum - Silvertree Forest - Cape Town 1.JPG
A young silvertree at Kirstenbosch Botanical Gardens, Cape Town
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Proteales
Family: Proteaceae
Genus: Leucadendron
Species:
L. argenteum
Binomial name
Leucadendron argenteum
Silvertree Distribution Map - Leucadendron argenteum - Cape Town.png
Map of the extant population of silvertrees in the Cape Peninsula
Synonyms [2]
  • Protea argenteaL.

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]

Contents

Appearance

Adult specimen growing on the eastern slopes of Table Mountain, near Rhodes Memorial. 2 Large Silvertree - Leucadendron argenteum - CT.jpg
Adult specimen growing on the eastern slopes of Table Mountain, near Rhodes Memorial.

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.

Distribution

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]

Status and conservation

Seeds of the silver tree Leucadendron argenteum - Silverleaf Tree seeds.jpg
Seeds of the silver tree

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.

Heraldry

"[S]tylized twigs of the silver tree" [ sic ] appear in the arms of the South Peninsula Municipality of South Africa. [7]

Pictures

See also

Related Research Articles

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<i>Leucospermum cuneiforme</i> Shrub in the family Proteaceae from the southern mountains 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.

<i>Leucospermum vestitum</i> Species of shrub in the family Proteaceae from the Western Cape 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.

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<i>Leucadendron spissifolium <span style="font-style:normal;">subsp.</span> fragrans</i> Subspecies of plant

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.

References

  1. Rebelo, A.G.; Mtshali, H.; Koopman, R.; Raimondo, D. (2020). "Leucadendron argenteum". IUCN Red List of Threatened Species . 2020: e.T30350A185568120. doi: 10.2305/IUCN.UK.2020-3.RLTS.T30350A185568120.en . Retrieved 19 November 2021.
  2. The Plant List: A Working List of All Plant Species , retrieved 27 December 2016
  3. "Protected Trees" (PDF). Department of Water Affairs and Forestry, Republic of South Africa. Archived from the original (PDF) on 5 July 2010. Retrieved 13 June 2013.
  4. "IDM Cape Peninsula - Ld arge". www.proteaatlas.org.za. Retrieved 2017-08-02.
  5. "Threatened Species Programme | SANBI Red List of South African Plants". redlist.sanbi.org. Retrieved 2017-08-02.
  6. "C Town to count cost of fires: South Africa: News: News24". Archived from the original on 2007-09-30. Retrieved 2006-01-27.
  7. "National Archives of South Africa (NASA) Database Selection".