A genus of about about 6 species (as more narrowly treated here), trees, shrubs, and subshrubs, of Eurasia, tropical Africa, and nw. North America.
Ref: Eyde (1987); Fan & Xiang (2001); Ferguson (1966c); Ferguson (1966d); Godfrey (1988); Kubitzki et al. (2004); Murrell (1993); Murrell & Poindexter (2016) In Flora of North America Editorial Committee (2016); Pais, Whetten, & Xiang (2016); Wilson (1965); Xiang et al. (2006); Xiang, Soltis, & Soltis (1998); Zhang et al. (2008). Show full citations.