Stirtonia, a new genus of the tribe Podalyrieae (Leguminosae) from South Africa

The genus Stirtonia is described to accommodate three anomalous species, hitherto placed in Podalyria . The new genus differs from Podalyria mainly in the decussate (geminate) inflorescence structure (racemose in Podalyria ), the yellow flower colour (purple, pink or white in Podalyria ), the non-fleshy rim-aril of the seeds (seed aril invariably fleshy and collar-like in Podalyria ) and in the diagnostically different combination of quinolizidine alkaloids. The major alkaloidal metabolites are carboxylic acid esters of lupanine and virgiline, but these compounds are totally absent in Podalyria . The morphology of inflorescences, leaves, flowers and seeds are described and illustrated. Chromosome numbers (2n = 18) are reported for the first time. A formal taxonomic treatment of the three species, S. tayloriana, S. chrysantha and S. insignis , is presented.