Leucospermum conocarpodendron

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Leucospermum conocarpodendron
Leucospermum conocarpodendron - Table Mountain 6.JPG
top subsp. conocarpodendron, bottom subsp. viridum
Leucospermum conocarpodendron ssp. viridum Betty's Bay 01.jpg
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
Order: Proteales
Family: Proteaceae
Genus: Leucospermum
Species: L. conocarpodendron
Binomial name
Leucospermum conocarpodendron
(L.) H.Buek
Synonyms[1]
  • Leucadendron conocarpodendron, Protea conocarpodendron, P. conocapa, Leucospermum conocarpum
  • P. tortuosa
  • Leucadendrum crassicaule
  • Leucospermum macowanii

Leucospermum conocarpodendron, is the largest species of the genus 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, with 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 natural occur near Cape Town, South Africa. Two subspecies are distinguished. L. conocarpodendron subsp. conocarpodendron, that has greyish leaves because they have a covering of felty hairs. L. conocarpodendron subsp. viridum, has green leaves that lack felty hairs. Flowers can be found between August and December.[1]

Leucospermum conocarpodendron

Early etching of Leucospermum conocarpodendron (left) and two Protea species by Arabella Elizabeth Roupell

L. conocarpodendron is an evergreen large shrub of 3–5 m (9.8–16.4 ft) high and 3–6 m (9.8–19.7 ft) in diameter with a rounded crown, which is rigid because of the thick branching at approximately right angles, and with a firm trunk of 15–40 cm (5.9–15.7 in) in diameter that is covered by 3–5 cm (1.2–2.0 in) thick greyish, reddish or blackish bark with a netting of fissures. The flowering branches are rigid, 1–1½ cm (0.4–0.6 in) thick and covered with a dense layer of white or greyish crinkly hairs or long soft silky hairs. The leaves lack a leaf stalk and stipules, ovate to lance-shaped with the greater width often beyond midlength 6–11½ cm (2.4–4.6 in) long and 2½–5 cm (1–2 in) wide, with a blunt or pointy tip, shallow or deeply incised with three to ten teeth. Dependent on the subspecies, the surface og=f the leaves is either hairless or has a dense covering of soft, greyish, convoluted hairs, occasionally with a fringe of fine hairs.[1]

The flower heads sit atop a stalk of about 1½ cm (0.6 in) long, are globe- to egg-shaped, and 7–9 cm (2.8–3.5 in) in diameter. They can be found individually or mostly with two or three together near the tip of the branch, regularly partly enclosed by leaves. The common base of the flowers of the same head is narrowly cone-shaped with a pointy tip, 2½–3 cm (1–1.2 in) long and 1–1½ cm (0.4–0.6 in) in diameter. The bracts that subtend the flower head are oval in shape with a point tip, 1¼–1½ cm (0.5–0.6 in) long and approximately 1 cm (0.39 in) wide, tightly overlapping, with a rubbery consistency and softly hairy. The bracts supporting the individual flowers enclose them at their base, have a suddenly pointed tip, and are about 2 cm (0.79 in) long, and about 1 cm (0.39 in) wide, rubbery in consistency, woolly at the base and less so near the top. The perianth is 3½–5 cm (1.4–2.0 in) long and yellow in colour. The lower 1 cm (0.4 in) is fused, cylindric, and hairless. The free parts of the four perianth claws curl back when the flower opens, those to the sides and facing the rim of the flower head densely set with long hairs. The one facing the center of the head minutely powdery or very shortly softly hairy. The perianth limbs are lance-shaped with a pointy tip, 6–8 mm (0.24–0.31 in) long, and have long hairs pressed to the surface, except for the one facing the center that is minutely powdery. The style is stout, 1–1½ mm (0.04–0.06 in) thick and 4½–5½ cm (1.8-2.2 in) long stout, 1.0 - 1.5 mm long, at first bent towards the center of the flower head but getting more straight with age. It is topped by a slight thickening that is called the pollen presenter, which has a broad conical shape with a pointy tip, is 4–5 mm (0.16–0.20 in) long and about 2 mm (0.079 in) wide. Subtending the ovary are four lance-shaped scales with a pointy tip of about 2 mm (0.079 in) long.[1]

The subtribe Proteinae, to which the genus Leucospermum has been assigned, consistently has a basic chromosome number of twelve (2n=24).[2]

Differences between the subspecies

The grey tree pincushion or vaalkreupelhout in Afrikaans (subsp. conocarpodendron) has felty hairy leaves due to a dense cover of fine crisped hairs, while the green tree pincushion or groenkreupelhout (subsp. viridum) has green hairless adult leaves, sometimes with a fringe of hairs rond the edge. At one location, on the east side of Little Lion's Head near Mount Rhodes, a hybrid swarm between both subspecies is found, where individual plants may have hairiness anywhere between that of both parents. Elsewhere, the populations are uniform and can easily be assigned to either of the subspecies.[1][3]

Differences with related species

L. conocarpodendron differs from its nearest relatives by its tree-like habit, the narrowly cone-shaped common base of the flower heads, the oval involucral bracts with a pointy tip, and the broad cone-shaped pollen presenter.[1]

Taxonomy

The earliest known description of the species we now know as Leucospermum conocarpodendron was by Paul Hermann in Paradisus Batavus, a book describing the plants of the Hortus Botanicus Leiden (botanical garden of the Leyden university), that was published in 1689, three years after his death. He called it Salix conophora Africana (African cone-bearing willow), based on his observation of Leucospermum conocarpodendron on the lower slopes of the Table Mountain. In the following six decades, several other descriptions were published, such as by Leonard Plukenet, James Petiver, John Ray and Herman Boerhaave. Names published before 1753, the year that was chosen as a starting point for the binominal nomenclature proposed by Carl Linnaeus, are not valid however.

The tree pincushion was first validly described in the first edition of Species Plantarum as with Leucadendron conocarpodendron by Linnaeus in 1753. Johann Jacob Reichard in 1779 reassigned the species to Protea, creating the new combination P. conocarpodendron. In 1781, Carl Peter Thunberg simplified the species name and created P. conocarpa, but because he used the same type as Linnaeus, he should have used the unchanged name. Richard Anthony Salisbury created two superfluous names, Protea tortuosa in 1796 and Leucadendrum crassicaule in 1809. In his book On the natural order of plants called Proteaceae that Robert Brown published in 1810, the species was reassigned to the new genus Leucospermum, but he combined it with Brown's invalid simplified species name to Leucospermum conocarpum. In 1874, Heinrich Wilhelm Buek made the correct combination Leucospermum conocarpodendron. Another form was described by Michael Gandoger in 1901, and he called it Leucospermum macowanii. In 1970, John Patrick Rourke proposed to distinguish between the typical subspecies (L. conocarpodendron subsp. conocarpodendron) and L. conocarpodendron subsp. viridum.[1]

L. conocarpodendron has been assigned to the section conocarpodendron.[4] The species and subspecies name conocarpodendron means "tree bearing cone-shaped fruits". The subspecies name viridum means green and is a reference to the leaves' colour. It was called kreupelhout in Dutch (cripple wood) already before 1680, a reference to the twisted branches that together give the tree a "crippled" appearance.[3]

Distribution, habitat and ecology

L. conocarpodendron subsp. conocarpodendron is an endemic of the Cape Peninsula where it is limited to the eastern slopes of Devils Peak, the northern and western slopes of Table Mountain and the Black Table, to Llandudno. It grows mainly on heavy clay resulting from the weathering of derived from Cape Granite but also weathered Table Mountain Sandstone. It prefers north and west exposures that are well drained.[1]

L. conocarpodendron subsp. viridum has a much wider distribution that borders on that of the typical subspecies. It occupies the remainder of the Cape Peninsula from Kirstenbosch to the Cape of Good Hope. In addition, it occurs from the upper Berg River Valley, via Pringle Bay and Hermanus to Stanford. Isolated populations can also be found at Helderberg, Simonsberg, and Kogelberg near Durbanville. It occurs is such different soil types as Malmesbury gravel, sand from weathered Table Mountain Sandstone, dune sands, permanently soggy peat, and sometimes on the heavy clay that remains if Cape Granite is decomposed. It mostly grows between sea level and 150 m (490 ft), sometimes 300 m altitude. At some locations this pincushion is dominant and develops dense stands.[1]

Both subspecies have some resistance for the wildfires that occur in the fynbos every one or two decades, because the trunk is covered by a thick bark. After the fire has burnt away the soft parts, regrowth takes place from the tip of the higher branches. Repeated mild burning results in an umbrella shaped growth habit.[1]

References

  1. ^ a b c d e f g h i j Rourke, John Patrick (1970). Taxonomic Studies on Leucospermum R.Br (PDF). pp. 49–57. 
  2. ^ Johnson, L.A.S.; Briggs, Barbara G. (1975). "On the Proteaceae—the evolution and classification of a southern family" (PDF). Botanical Journal of the Linnean Society. 70 (2): 106. 
  3. ^ a b "Leucospermum conocarpodendron subsp. conocarpodendron and subsp. viridum". SANBI. 
  4. ^ "Identifying Pincushions". Protea Atlas Project. 
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