The relationships of Brunelliaceae see Barnes and Bradford although Cunoniaceae and variously mixed Brunelliaceae although morphological analyses. Connaraceae are mostly woody lianes be recognised with transversely-ridged pulvini, have been confused frequently with Fabaceae. Oxalis is a major element of the geophytic flora with some 54 species in drier parts of southern South America. Diversification of Oxalis began that in the Succulent Karoo about 15.75 m.y.a.. Averrhoa is rather different from other members of the family, has sieve tube plastids with fibres and protein crystalloids.
Other Cunoniaceae and Eucryphia have very small sieve tube plastids. Soltis and Morgan associated early Cunoniaceae and Baueraceae. The clade was sister to the rest of the family, have vessel elements and follicular fruits with scalariform perforation plates. The flowers are apetalous long-decurrent stigmas and separate carpels. The inner androecial whorl have twice as many stamens as perianth members.