The Rutaceae are a large family of aromatic trees, shrubs, and sometimes herbs consisting of approximately 171 genera. This family contains many members of economic importance, most notably the Citruses for their edible fruits and aromatic oils used for perfumery and medicines, and for timber, as well as ornamentals. The family has a more or less cosmopolitan distribution, but is largely centered in the tropics and temperate regions of the Southern hemisphere, especially Australia and South Africa. The Rutaceae in general are characterized by: the presence of secretory cavities containing aromatic ethereal oils usually scattered throughout the parenchyma and in the pericarp, sieve-tubes with S-type plastids, estipulate leaves, and a superior ovary. All other characters at this level manifest a bewildering diversity of character states, especially in regards to the flower and fruit morphology. The most recent monograph on a worldwide basis and the only systematic treatment of Rutaceae is that of Engler (1896, with revisions in 1931), which recognized seven subfamilies: Rhabdodendroideae, Citroideae (Aurantioideae), Flindersioideae, Spathelioideae, Dictyolomatoideae, Rutoideae, and Toddalioideae. The circumscription of the Rutaceae and the placement of these subfamilies has changed in recent years. Flindersioideae, Dictyolomatoideae, Spathelioideae and Rhabdodendroideae have been placed in various families while suggestions have been made regarding the combination of the Rutoideae and Toddalioideae (Quader et al. 1991). Currently Rhabdodendroideae is recognized as a separate family within Caryophyllales. This study of the rbcL, atpB and atpB-rbcL spacer sequences aims to assesses molecular support for the subfamilial and tribal circumscriptions. The resulting tree shows Rutaceae to be paraphyletic: Citroideae are monophyletic; Flindersioideae belong in Rutaceae, but the two genera are not monophyletic; Dictyolomatoideae and Spathelioideae are by default monophyletic, but both appear to be part of a clade that includes Harrisonia, Cneorum, and Ptaeroxylon; and Toddalioideae should be merged with Rutoideae.

Key words: chloroplast genes, molecular systematics, Rutaceae