Chemotaxonomy, variation and geographical distribution of the Empetraceae

Abstract

Thirty-one flavonoids (and related phenolics) were found in leaves of the six species in the three genera of Empetraceae (90 populations studied) and five further pigments in fruits of Empetrum. Affinity with the Ericaceae is supported by the occurrence of the 3-galactosidesof gossypetin, malvidin, delphinidin, cyanidin and peonidin. The distribution of leaf flavonoids agrees with both the recognition of three genera and species-delimitation in Ceratiola and Corema. In Empetrum, the flavonoids differ modally in the three species usually accepted, thus confirming data on fruit colour and breeding systems, and suggesting that the genus comprises one species with about three subspecies at diploid and tetraploid levels. The black fruits of most Northern Hemisphere plants contain malvidin, petunidin and delphinidin, while the red fruits of almost all Southern Hemisphere populations (E. rubrum) contain cyanidin and peonidin and provide a rare example of the association of cyanidin (instead of delphinidin) with the wild-type allele. In leaf flavonoid content the diploid E. nigrum is much closer to its presumed tetraploid derivative E. eamesii than to the diploid E. rubrum, which differs most from E. eamesii. Flavonoid patterns and breeding system distinguish most E. rubrum populations from those isolated in Tristan da Cunha-Gough Island. The phytogeographical importance of the phytOGhemical results is discussed.