THE CHEMOTAXONOMY OF GERANIUM (GERANIACEAE)

Relationships among Geranium species constituting sectt. Anemonifolia, Lucida (monotypic) and Ruberta together with representatives of sect. Unguiculata were investigated by gas-chromatographic study of essential oils, electrophoretic comparison of seed proteins and chromatographic separation of nectar amino acids. - Essential oil study gave little information. G. macrorrhizum (sect. Unguiculata) had far greater quantities of essential oils in its foliage than other species and differed from them qualitatively. - Species of sectt. Anemonifolia and Ruberta, together with G. cataractarum (sect. Unguiculata), between them yielded 19 seed protein bands; the distribution of these indicated close relationship among the species and was consistent with hypotheses for the origin of certain species by alloand autopolyploidy partly within the group. Involvement of an unknown species in the origin of two allopolyploids was implied. Separate origins for the two octoploid species in this set are also inferred. In two instances there was evidence for the transformation of one band into another subsequent to the separation of related species. The inference of allopolyploidy was supported by the occurrence of additivity of parental bands shown by an artificial hybrid between two of the species. A model for the evolutionary divergence of the seed protein patterns is presented. Two species outside the above set appeared less closely related; they were G. lucidum and G. macrorrhizum (sect. Unguiculata) and between them they showed 6 additional bands, four of which were shared. - Of 18 nectar amino acids found, 4 to 15 occurred in any one species, with low numbers (4 and 8) occurring in the most extreme inbreeders. The spectra of nectar amino acids of two hybrids showed additivity of those of the respective parents. The results echo rather closely those provided by seed proteins, but in the absence of data from outside the group their taxonomic significance is uncertain. However, the divergence between the two octoploids was again evident. © 1990 Springer-Verlag.