Codon was long regarded as an odd member of Hydrophylloideae, but in 1998, a molecular phylogenetic study suggested that it is closer to Boraginoideae.

Subsequently the order Boraginales was added to the 2016 revision (APG IV) to include Boraginaceae at the ordinal level, in which it was the sole family.

The consensus was to continue the broad usage rather than split it into separate families, based on its monophyletic composition.

[citation needed] Comparisons of DNA sequences by cladistic methods suggested the division of Boraginoideae into four tribes: Echiochileae, Boragineae, Lithospermeae, and Cynoglosseae.

[2] Genera and approximate number of species in the system of Chacon et al (2016):[2] Anchusa, Anchusella, Borago, Brunnera, Cynoglottis, Gastrocotyle, Hormuzakia, Lycopsis, Melanortocarya, Nonea, Pentaglottis, Phyllocara, Pulmonaria, Symphytum, Trachystemon Moritzia, Thaumatocaryon Aegonychon, Alkanna, Ancistrocarya, Arnebia, Buglossoides, Cerinthe, Cystostemon, Echiostachys, Echium, Glandora, Halacsya, Huynhia, Lithodora, Lithospermum, Lobostemon, Maharanga, Mairetis, Moltkia, Moltkiopsis, Neatostema, Onosma, Paramoltkia, Podonosma, Pontechium, Stenosolenium.