The use of flavonoids in the taxonomy of Boykinia and allies (Saxifragaceae)

Abstract

All taxa of Suksdorfia, Hieronymusia, and Boykinia (including the segregates Neoboykinia, Peltoboykinia, and Telesonix), and one species each of Bolandra and Sullivantia were examined for their flavonoids. A diverse array of flavone and flavonol mono-, di-, and tri-glycosides was found. 3-O-Methylation and 6-oxygenation were common, as was 3, 7-O-triglycosylation. Groups of flavonol monoglycosides with either charged or acetylating functions were also observed. Taxonomically, the flavonoid relationships are many, various, and somewhat reticulate, indicating a close relationship among all taxa. The data provide only limited help in defining generic limits. They do, however, support the placement of Boykinia jamesii in Boykinia, or near it (as Telesonix), rather than in Saxifraga. The data also favour the retention of Neoboykinia within Boykinia. The exceptionally simple flavonoid profile of Boykinia tellimoides could support its elevation to generic rank (Peltoboykinia) were it made on other grounds. The evolutionary trends of flavonoid reduction and diversification are seen operating in the genera. Parallelism involving several different flavonoid structures is common in the Saxifraginae and supports the inclusion of Chrysosplenium in the subtribe.