The most recent classification of Quercus divides the genus into two subgenera and eight sections. These divisions support the evolutionary diversification of oaks among two distinct clades: the "Old World" clade, including oaks that

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Records of Quercus have been reported from Late Cretaceous deposits in North America and East Asia, however these are not considered definitive. In a survey of the fossil record of Quercus it was concluded that "pre-Paleogene, and perhaps pre-

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Interspecific hybridizationis quite common among oaks, but usually between species within the same section only, and most common in the white oak

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Oaks are keystone speciesin a wide range of habitats from Mediterranean semi-desert to subtropical rainforest. For example, oak trees are important components of hardwood forests, and certain species are particularly known to grow in associations with

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Sudden oak death (Phytophthora ramorum) is a water mould that can kill oaks within just a few weeks. Oak wilt, caused by the fungus

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According to a comprehensive report by The Morton Arboretumand the International Union for Conservation of Nature (IUCN) an estimated 31% of the world's estimated 430 oak

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Oak wood has a density of about 0.75 g/cm (0.43 oz/cu in) creating great strength and hardness. The wood is very resistant to insect and fungal attack because of its high tannin content. It also has very appealing grain markings, particularly when

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