| The evolutionary histories of various stylar conditions (heterostyly, enantiostyly, stylar dimorphism and monomorphism) were examined in two groups of monocotyledons, Pontederiaceae and Narcissus, using several sources of phylogenetic information and several different weighting schemes for reconstructions of character evolution.; The monophyly of Pontederiaceae is strongly supported by phylogenetic evidence from rbcL, but its local position in the monocotyledons is unclear. Several tests were used to assess the congruence of four phylogenetic data sets for the family: two chloroplast genes (ndhF and rbcL); a restriction-site survey of the plastome; and a revised morphology-based data set. Despite different "rules" of evolution for the three chloroplast sources of data, these data sets provided highly congruent, well resolved and well supported phylogenetic estimates of the family's history. The morphological data provided a poorly supported phylogenetic estimate that showed both congruence and incongruence with the chloroplast evidence.; A combined analysis of ndhF and rbcL genes from taxa in five superorders of monocotyledons added support to the view that three families containing enantiostylous taxa, Commelinaceae, Haemodoraceae and Philydraceae, are the nearest living relatives of Pontederiaceae. Several lines of evidence indicate that despite the evolutionary distance between Pontederiaceae and these families, they contain useful historical information concerning the position of the family's root.; Trees derived from the combined chloroplast evidence were used to reconstruct breeding-system evolution in Pontederiaceae. Moderately weighted optimization schemes indicate that tristyly arose once only in the family, while predominantly-selfing, florally-monomorphic lineages of Eickhornia arose on multiple occasions. Self-incompatibility arose after the origin of the floral trimorphism, a scenario incompatible with some evolutionary models. Enantiostyly arose twice, with its occurrence in Heteranthdera (sensu lato) possibly homologous with that in related families.; Reconstructions of breeding-system evolution in Narcissus are impeded by the partial lack of resolution of an ndhF-based tree of the genus and the probable role played by undetected hybridization events in the genus' phylogenetic history. A preliminary reconstruction of breeding-system evolution in Narcissus suggests that stigma-height dimorphism may have arisen on multiple occasions, and that tristyly in Narcissus triandrus may have evolved directly from floral monomorphism. |
