Boraginoideae is a subfamily of the flowering plant family Boraginaceae, as that family is defined in the APG III system of classification for flowering plants. The Angiosperm Phylogeny Group has not actually specified subfamilies within Boraginaceae. Some taxonomists place the genera Codon and Wellstedia in Boraginoideae. Others place one or both of these in separate, monogeneric subfamilies. Codon was long regarded as an odd member of Hydrophylloideae, but in 1998, a molecular phylogenetic study showed that it is closer to Boraginoideae.