The Flavonoids and Flavonoid Systematics of Circaea (Circaeeae, Onagraceae)

Abstract

Foliar flavonoid data are given for 13 of the taxa recognized in Circaea and for six of the nine known naturally occurring hybrids. Analysis of 113 populations revealed the presence of eight glycoflavones, two flavones, and two flavonols in the genus. The glycoflavones are orientin, isoorientin, isoorientin O-acylate, vitexin, vitexin O-acylate, isovitexin, isovitexin O-acylate, and vicinin-1. Apigenin 7-O-glucoside and luteolin 7-O-glucoside are the two flavones and kaempferol 3-O-glucoside and quercetin 3-O-glucoside are the two flavonols. Circaea differs from other genera of the Onagraceae investigated in exhibiting considerable interspecific and interpopulational variation in flavonoid composition. Two groups of species can be recognized in Circaea based on flavonoid data; the same two groups are also recognized using morphological criteria. As in other Onagraceae, Circaea shows reduction in structural diversity and overall number of compounds with evolutionary advancement.