The family has only recently been recognized by taxonomists. The APG IV system of 2016 (unchanged from the 1998, 2003, and 2009 versions) does recognize this family.[1][3] The family then includes over half a dozen genera, with only a few dozen species, occurring in Africa, in western South America and western North America. This circumscription includes the genus Cyanastrum, which sometimes has been treated as a separate family Cyanastraceae.
^Angiosperm Phylogeny Group III (2009), "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III", Botanical Journal of the Linnean Society, 161 (2): 105–121, doi:10.1111/j.1095-8339.2009.00996.x, hdl:10654/18083