Agathis

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Agathis, commonly known as kauri or dammara, is a genus of evergreen coniferous trees, native to Australasia and Southeast Asia. It is one of three extant genera in the family Araucariaceae, alongside Wollemia and Araucaria (being more closely related to the former).<ref name="POWO"/><ref name="Laubenfels">de Laubenfels, David J. 1988. Coniferales. P. 337–453 in Flora Malesiana, Series I, Volume 10. Dordrecht: Kluwer Academic.</ref> Its leaves are much broader than most conifers. Kauri gum was historically commercially harvested from living New Zealand kauri and from swamp ground.Template:Not verified in body

Description

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Trunk of Agathis robusta at Cairns Botanic Gardens

Mature kauri trees have characteristically large trunks, with little or no branching below the crown. In contrast, young trees are normally conical in shape, forming a more rounded or irregularly shaped crown as they achieve maturity.<ref name="Whitmore">Whitmore, T.C. 1977. A first look at Agathis. Tropical Forestry Papers No. 11. University of Oxford Commonwealth Forestry Institute.</ref>

The bark is smooth and light grey to grey-brown, usually peeling into irregular flakes that become thicker on more mature trees. The branch structure is often horizontal or, when larger, ascending. The lowest branches often leave annular branch scars when they detach from the lower trunk.

The juvenile leaves in all species are larger than the adult, more or less acute, varying among the species from ovate to lanceolate. Adult leaves are opposite, elliptical to linear, very leathery and quite thick. Young leaves are often a coppery-red, contrasting markedly with the usually green or glaucous-green foliage of the previous season.

The male pollen cones appear usually only on larger trees after seed cones have appeared. The female seed cones usually develop on short lateral branchlets, maturing after two years. They are normally oval or globe shaped.

Seeds of some species are attacked by the caterpillars of Agathiphaga, some of the most primitive of all living moths.

Uses

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Agathis australis logs and loggers near Piha

Various species of kauri give diverse resins such as kauri gum. The timber is generally straight-grained and of fine quality with an exceptional strength-to-weight ratio and rot resistance, making it ideal for yacht hull construction. The wood is commonly used in the manufacture of guitars and ukuleles due to its low density and relatively low price of production. It is also used for some Go boards (goban). The uses of the New Zealand species (A. australis) included shipbuilding, house construction, wood panelling, furniture making, mine braces, and railway sleepers. Due to the hard resin of the wood, it was the traditionally preferred material used by Māori for wooden weapons, patu aruhe (fernroot beaters) and barkcloth beaters.<ref>Template:Cite Q</ref>

Evolutionary history

Within Araucariaceae, it is thought that Agathis and Wollemia share a common ancestor which lived between 90 and 55 million years ago, and the two genera form a sister clade to the older Araucaria.<ref>Complete Chloroplast Genome of the Wollemi Pine (Wollemia nobilis): Structure and Evolution</ref> The oldest fossils currently confidently assignable to Agathis are those of Agathis immortalis from the Salamanca Formation of Patagonia, which dates to the Paleocene, approximately 64.67–63.49 million years ago. Agathis-like leaves are also known from the slightly older Lefipán Formation of the same region, which date to the very end of the Cretaceous.<ref>Template:Cite journal</ref> Some authors have suggested that Agathis is known from earlier in the Cretaceous (Aptian to Cenomanian in North Africa.<ref>Template:Cite book</ref> Other fossils of the genus are known from the Eocene of Patagonia, the Late Paleocene-Miocene of southern Australia, and the Oligocene-Miocene of New Zealand.<ref>Template:Cite journal</ref>

Species list

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Accepted species<ref name="POWO"/>
Image Scientific name Common name Distribution
Agathis atropurpurea black kauri, blue kauri Queensland, Australia
Agathis australis New Zealand kauri North Island, New Zealand
Agathis borneensis Borneo kauri western Malesia, Borneo
Agathis dammara Sulawesi kauri Philippines, Sulawesi, Maluku Islands
  Agathis flavescens Tahan Agathis Peninsular Malaysia
Agathis kinabaluensis Kinabalu kauri Borneo
  Agathis labillardierei New Guinea kauri New Guinea
Agathis lanceolata Koghi kauri New Caledonia
  Agathis lenticula Sabah kauri Borneo
Agathis macrophylla (syn. A. vitiensis) Pacific kauri, dakua Fiji, Vanuatu, Solomon Islands
Agathis microstachya bull kauri Queensland, Australia
  Agathis montana New Caledonia
Agathis moorei white kauri New Caledonia
  Agathis orbicula Sarawak kauri Borneo
Agathis ovata Scrub kauri New Caledonia
Agathis robusta Queensland kauri Queensland, Australia; Papua New Guinea
  Agathis robusta subsp. robusta Queensland and Papua New Guinea
  Agathis robusta subsp. nesophila New Guinea kauri Papua New Guinea
  Agathis silbae Vanuatu
  Agathis zamunerae Patagonia, South America Argentina
Formerly included<ref name="POWO"/>

Moved to Nageia

The placement of the fossil species "Agathis" jurassica from the Late Jurassic of Australia in this genus is doubtful.<ref name="HillBrod99">Template:Cite journal cited in Template:Cite book</ref>

References

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