Alkaloids as taxonomic characters in the tribe Crotalarieae (Fabaceae)

Recent studies of alkaloids have led to a better understanding of the intricate taxonomic relationships in the tribe Crotalarieae. Data from alkaloidal metabolites are largely congruent with morphological data, but allow refinement of the understanding of the phylogeny. A well-supported and almost fully resolved cladogram is presented, which shows that the genera can be grouped into four main clades: (1) an unspecialized group without α-pyridone alkaloids and without esters of alkaloids (Aspalathus, Lebeckia, Rafnia, Wiborgia and perhaps Spartidiurn); (2) a group specializing in lupanine-type esters (Pearsonia and Rothia); (3) a group with macrocyclic pyrrolizidine alkaloids (Crotalaria andLotononis); and (4) a specialized group with α-pyridone alkaloids (Argyrolobium, Dichilus, Melolobium and Polhillia).