Loganiaceae R. Brown ex Martius.
As here rather narrowly interpreted, Loganiaceae consists of about 16 genera and about 460 species, herbs, shrubs, and trees, of tropical, subtropical, and warm temperate areas of the Old and New Worlds (Struwe et al. 2018). Other genera in our area which have traditionally been considered components of the Loganiaceae now are clearly better placed in the small families Tetrachondraceae (Polypremum), Gelsemiaceae (Gelsemium), and Scrophulariaceae (Buddleja), more closely related to other families (such as Rubiaceae) than to Loganiaceae sensu stricto (Struwe, Albert, & Bremer 1994). The affinities of Spigelia appear to be with a small group of tropical and subtropical genera, the largest of which is Strychnos. Struwe, Albert, & Bremer (1994) treated this group as the family Strychnaceae, based on a cladistic analysis of data. A later, more thorough analysis suggested that Strychnaceae is best recombined with Loganiaceae (Backlund, Oxelman, & Bremer 2000).