FLAVONOIDS OF THE MENYANTHACEAE: INTRA‐ AND INTERFAMILIAL RELATIONSHIPS

Abstract

This paper describes our study of the flavonoid chemistry of the Menyanthaceae, which included Menyanthes, Fauria (= Nephrophyllidium), Liparophyllum (all monotypic), nine species of Nymphoides, and 11 species of Villarsia. The flavonoid profiles are based upon kaempferol, 7‐O‐methylkaempferol, quercetin, 7‐O‐methylquercetin, isorhamnetin, 3,7‐di‐O‐methylquercetin, and 7,3′‐di‐O‐methylquercetin, although not all taxa exhibit all of these aglycones. These compounds occur as a complex mixture of 3‐O‐mono‐ and 3‐O‐diglycosides; 4′‐O‐glucosides were restricted to four species of Nymphoides. Some acylated glycosides were also observed. The presence of flavonols and absence of both C‐glycosylflavones and xanthones set the Menyanthaceae apart from the Gentianaceae, the family with which it is most often allied. Flavonoid data do not allow assignment of the Menyanthaceae with surety to either the Gentianales or Solanales. The flavonoid profiles of Liparophyllum and Fauria are unique within the family and do not support a close affinity of the latter genus to Menyanthes. A close relationship between Nymphoides and Villarsia, suggested on morphological grounds, is supported by the flavonoid data. Flavonoids support the view, based upon morphology, that the South African Villarsia capensis is more closely related to eastern Australian Villarsia species than to Western Australian ones that are geographically closer. Segregation of Nymphoides fallax from other Meso‐American and Caribbean taxa is supported by the flavonoid data. Flavonoid data also support the view that N. indica is a circumtropical taxon not deserving separate species status in the New World.