Phylogenetic relationships of the Juglandaceae

A cladistic analysis of molecular data from the chloroplast gene rbcL was used to examine the taxonomic relationships of the walnut family (Juglandaceae). In addition, chemical and morphological data from a previous study by Hufford (1992) were incorporated, expanded, and analyzed independently and in combination with the molecular data. The results of these analyses suggest that the Juglandaceae are more closely related to the Fagaceae, Betulaceae, Casuarinaceae, and Urticaceae and their relatives (sensu Cronquist 1981) than they are to the Anacardiaceae (sensu Thorne 1983). However, sequence data from rbcL also suggest a relationship between the higher Hamamelidae and certain families in the Rosidae sensu Cronquist 1981 (such as Rosaceae and Rhamnaceae), an outcome which would add credence to the widely accepted view of the polyphyletic nature of the Hamamelidae.