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Julian Sutton (2019)
Sutton, J. (2019), 'Davidia' from the website Trees and Shrubs Online (treesandshrubsonline.
A medium sized, deciduous tree endemic to central China, whose small inflorescences of inconspicuous flowers are subtended by pairs of highly conspicous and ornamental white bracts (Qin & Phengklai 2007).
Davidia has a single living species, D. involucrata. However, fossil fruits and leaves of one or more extinct species are known from Palaeocene deposits in the northern USA and eastern Russia, and fruits have been reported from the Pliocene and Pleistocene of Japan (Manchester 2009 and references therein). It seems that Davidia is a classic example of a Tertiary relict genus. Such groups were widely distributed across the northern continents in the early part of the Tertiary era. Changing climates subsequently restricted their ranges, usually to areas within East Asia (Milne & Abbott 2002).
The generic name commemorates Armand David, the French missionary-botanist, who first brought this tree to the attention of western science, along with that most celebrated Chinese relict species, the Giant Panda.
In horticultural literature, Davidia can be found placed in any of the following families: Cornaceae, Davidiaceae and Nyssaceae. This may give the false impression that its relationships are poorly understood. It has long been recognised that Nyssa and Camptotheca are the closest living relatives of Davidia, and that these genera are in turn related to Cornus and its allies. While ongoing research has refined our understanding of these relationships (for example He et al. 2004), it is ultimately the judgement and attitudes of the individual taxonomist that determine where the lines between families are drawn. Hence these three genera were included in a broadly defined Cornaceae by Eyde (1988), while Takhtajan (1980) considered Davidia distinct enough to be separated in a monotypic family, Davidiaceae. Here, we follow the Angiosperm Phylogeny Group (APG & APG 2001–2008) in grouping Davidia and Camptotheca with Nyssa in Nyssaceae.