A recent survey of sequence variation of a chloroplast-encoded gene yielded results indicating that tribes Cheloneae and Gratioleae are not monophyletic and that the Scrophulariaceae may consist of three independently derived lineages within the order Scrophulariales (DePamphilis et al.
Yet all these flower shapes are probably derivatives of open, bell-shaped, bee-pollinated corollas, since these occur throughout the Scrophulariales (Pennell, 1935; Bentham, 1876).
Convergences in flower morphology occur frequently between the families of the Scrophulariales.
The Salvadoraceae can still be found in the Celastrales, the Columelliaceae in the Hydrangeales (suborder Escalloniineae), the Convolvulaceae and Cuscutaceae in the Convolvulales, and, finally, the Buddlejaceae and Retziaceae he placed in the Scrophulariales .
The Escalloniaceae, a present-day taxon of this complex, is of interest, in particular the genus Tetracarpaea, which has an apocarpous gynoecium and tetramerous flowers, this first character being associated with the Apocynaceae and the latter with the Scrophulariales via the Buddlejaceae.