''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 Araucariaceae is a Family (biology), family of conifers with three living Genus, genera, ''Araucaria'', ''Agathis'', and ''Wollemia''. While the family's native distribution is now largely confined to the Southern Hemisphere, except for a few spe ...

, alongside '' Wollemia'' and ''

Araucaria ''Araucaria'' (; original pronunciation: .ɾawˈka. ɾja is a genus of evergreen coniferous trees in the family Araucariaceae. While today they are largely confined to the Southern Hemisphere, during the Jurassic and Cretaceous they were glo ...

'' (being more closely related to the former).de Laubenfels, David J. 1988. Coniferales. P. 337–453 in Flora Malesiana, Series I, Volume 10. Dordrecht: Kluwer Academic. Its leaves are much broader than most conifers. Kauri gum is commercially harvested from New Zealand kauri.

Description

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.Whitmore, T.C. 1977. ''A first look at Agathis''. Tropical Forestry Papers No. 11.

University of Oxford The University of Oxford is a collegiate university, collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the List of oldest un ...

Commonwealth Forestry Institute. 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 In mathematics, the term ''linear'' is used in two distinct senses for two different properties: * linearity of a '' function'' (or '' mapping''); * linearity of a '' polynomial''. An example of a linear function is the function defined by f(x) ...

, 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

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.

Evolutionary history

Within

, 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.'' The oldest fossils currently confidently assignable to ''Agathis'' are those of ''Agathis immortalis'' from the Salamanca Formation of Patagonia, which dates to the

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

, 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. Some authors have suggested that ''Agathis'' is known from earlier in the Cretaceous (

Aptian The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

in North Africa. Other fossils of the genus are known from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

of Patagonia, the Late Paleocene-

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

of southern Australia, and the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

-Miocene of New Zealand.

Species list

;Accepted species ;Formerly included Moved to '' Nageia'' * ''Agathis motleyi - Nageia motleyi'' * ''Agathis veitchii - Nageia nagi'' The placement of the fossil species '' "Agathis" jurassica'' from the Late Jurassic of Australia in this genus is doubtful. cited in

Gallery

File:'Lord of the Forest' Tane Mahuta.jpg, Tāne Mahuta, an '' Agathis australis'' in Waipoua Forest, the largest tree in New Zealand by volume File:Te Matua Ngahere.jpg, Te Matua Ngahere, an ''A. australis'' in Waipoua Forest, the oldest (and 2nd largest) tree in New Zealand File:Yakas kauri tree trunk 2.jpg, Trunk of the Yakas kauri (7th largest) File:Agathis lanceolata.jpg, ''Agathis lanceolata'' File:Agathis ovata 2.jpg, ''Agathis ovata'' File:AgathisMacroCones.jpg, ''Agathis macrophylla'' File:Agathisrobusta.JPG, ''Agathis robusta'' File:Agathis borneensis - feuilles.JPG, ''Agathis borneensis'' File:KauriFruchtstand.jpg, '' Agathis australis'' male pollen cone File:KauriSamen.jpg, Scale from '' Agathis australis'' female cone File:Kauricone01.jpg, '' Agathis australis'' cone File:Agathis australis foliage and cones.jpg, '' Agathis australis'' leaves and cones

References

External links

Systematics of ''Agathis'' (archived copy)

Kauri forest
in '' Te Ara: The Encyclopedia of New Zealand''
Threatened Conifers of the World
* https://www.researchgate.net/publication/309508851_A_reconstruction_of_the_palaeoecology_and_environmental_dynamics_of_the_Bahariya_Formation_of_Egypt {{Authority control Conifer genera