Distribution of alkaloids and tannins in the Crassulaceae

Abstract

Alkaloid and tannin levels of 36 species of the Crassulaceae were compared. The taxa investigated were Crassula multicava, Echeveria venezuelensis, Pachyphytum compactum, Kalanchoe (two spp.), Bryophyllum daigremontianum, Sedum (23 spp.), Aeonium (four spp.) and Sempervivum (three spp.). Apart from the alkaloidal species of Sedum, only E. venezuelensis was found to contain piperidine alkaloids, i.e. pelletierine and N-methyl pelletierine. Proanthocyanidins (condensed tannins) and galloyl esters were found in all genera, but they were absent from six out of 11 Sedum species containing piperidine alkaloids. The results indicate a dichotomy between the distribution of alkaloids and tannins, which is in good agreement with the major evolutionary trends within the family as inferred from chloroplast DNA restriction site variation. The distribution of alkaloids appears to be limited to the “ Acre” lineage, which comprises the Asian, Eurasian and American Sedum species with a reticulate testa as well as the Central American Sedoideae and Echeverioideae. The parallel occurrence of alkaloids and a complex of apparently primitive flower and seed characters in the terminal “ Acre” clade indicate the derived rather than the primitive condition of the latter features. The most parsimonious explanation for this marked inconsistency is a reversal of the floral structure at the basis of the “ Acre” lineage, mimicking the floral structure of ancestral angiosperms.