Flavonoid Distribution in the Aurantioideae (Rutaceae)

Abstract

In the Aurantioideae (Rutaceae), the advance in morphological spe- cialization is accompanied by an increased complexity of flavonoid constituents. The capacity for C-glycosylation is retained throughout the subfamily. As morphological development proceeds from the remote citrus relatives to the more highly specialized true citrus fruit trees, flavone 0-glycosides tend to replace flavonol 0-glycosides except for Balsamocitrinae, where flavonols predominate. Distribution of flavanones is restricted to Pleiospermium and to the six genera of the true citrus fruit trees. Similarities in the flavonoid profiles of Citrinae and Balsamocitrinae support Swin- gle's (1943) taxonomic concept of the subfamily. SYSTEMATICS OF THE AURANTIOIDEAE In the first modern classification of the Aurantioideae (Rutaceae), En- gler (1931) recognized a single tribe, Aurantieae, with two subtribes: Hesperethusinae and Citrinae. Tanaka (1932) subsequently divided the subfamily into eight tribes and eight subtribes, while Swingle (1938, 1943) accepted two tribes, each with three subtribes. Each of the presen- tations commences with the relatively unspecialized remote citroids (Mi- cromelum Blume, Glycosmis Correa) and proceeds toward the highly spe-