Phenotypic correlations among plant parts in Iberian Papilionoideae (Fabaceae)

Different plant organs may show varying degrees of form diversification or conservatism across phylogenetically related taxa. The present study uses data from a recent systematic study of Iberian Papilionoideae to investigate diversification and covariation in reproductive and vegetative plant parts. The appropriateness of imprecise (but comprehensive) taxonomic quantitative information is tested.

Organ size covariation and phenotypic correlations were studied among tribes, genera and species. Scale relationships were investigated by Reduced Major Axis regression. Variables used were the maximum dimensions of calyx, corolla, keel petal, fruit, seed, stipule, leaflet and petiole.

As regards tribe averages, the length of the corolla and that of calyx correlated positively and significantly. In contrast, pod length was unrelated to corolla size and largely tribe-specific. Within genera, the sizes of calyx, corolla and fruit sometimes covaried linearly (e.g. Lathyrus species) and other times did not (Genista, Astragalus).

Information from taxonomic studies can be useful to establish major phenotypic correlations in plants. Results underscore the implications of tribal ownership in the Papilionoideae and illustrate the extensive morphological diversification of pods relative to flowers in this group.