The homology of red flower colour in Crassula, cotyledon and Tylecodon (Crassulaceae)

The chemical basis of red flower pigmentation in species of Cotyledon, Crassula and Tylecodon is reported. Only six major anthocyanins were found in the 10 species and 22 samples investigated, and each of the genera had a characteristic combination of compounds. Crassula flowers invariably have only two of the major pigments, the 3-glucosides of cyanidin and peonidin. In Cotyledon, cyanidin-3-sophoroside is the dominant pigment in most of the samples and cyanidin-3-sambubioside only in some of them. This is also the major anthocyanin in orange-coloured Tylecodon flowers, but relatively high yields of delphinidin-3-sambubioside are found in dark red flowers. The anthocyanins reflect the close taxonomic relationship between Cotyledon and Tylecodon, and the more distant affinity of both genera with Crassula.