Cornaceae Berchtold ex J. Presl. Dogwood Family.

Contributed by Derick B. Poindexter, Zack E. Murrell, and Alan S. Weakley

Key to Cornaceae

A family of 5-6 genera (as here interpreted) and about 50-85 species, trees, shrubs, lianas, and subshrubs, semicosmopolitan (mainly northern hemisphere). The Cornaceae is best circumscribed to exclude Nyssa, which probably is not even sister to Cornaceae (Xiang et al. 2002; Fu et al. 2019). The generic limits within core Cornaceae have long been controversial. The segregate genera of Cornus used here date back to 1756-1839, and in the southeastern United States, Small (1903, 1913, 1933) treated our native species in Cynoxylon and Svida. Phylogenetic analyses show that Cornus treated very broadly is monophyletic, but various clades within it are also monophyletic and have ages and levels of genetic and morphologic divergence generally regarded as warranting generic distinction. Fu et al. (2019) estimated that the five major clades (including four in our area) have divergence times of 60-75 million years ago (about at the end of the Cretaceous). Yu et al. (2017) estimated that the major clades in Cornaceae (including the separation between Alangium and Cornus s.l.) date to 66-85 million years ago, with the exception of a more recent split between the big-bracted dogwoods (here treated as Benthamidia) and the dwarf cornels (here treated as Chamaepericlymenum). In all other families of the Cornales, clades with divergence times of such age are universally treated as separate genera, and separation times of half that are often accorded genus rank. Based on our increased knowledge of the age and distinctiveness of these groups, it seems almost certain that the traditional ‘subgenera’ will be recognized by consensus in the future as warranting generic rank, and we treat them so here. That consensus has not yet arrived: Eyde’s (1987) irritated and impassioned defense of a "broad Cornus" remains influential and is still followed by many -- though its reasoning seems increasingly irrelevant following a third of a century’s elucidation of the relationships within Cornaceae and related families. Cornaceae is represented in the southeastern United States by native members of three of the five major clades (here treated as genera: Swida, Benthamidia, and Chamaepericlymenum) and by a fourth clade (genus Cornus sensu stricto).

ID notes: The entire leaves with strongly arching secondary (lateral) veins are a distinctive feature of the Cornaceae.

Ref: Eyde (1987); Fu et al. (2019); Hara (1948); Kubitzki et al. (2004); Murrell & Poindexter (2016) In Flora of North America Editorial Committee (2016); Thomas et al. (2021); Xiang et al. (2002); Yu et al. (2017). Show full citations.

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