Phylogeny and Androecial Diversification of Loasaceae

Washington State University, Pullman WA

Investigators

Abstract

0075249 Hufford Systematics research includes the study of phylogenetic or genealogical relationships among species and genera, and the analysis of how morphological diversity arises within lineages. Dr. Larry Hufford at Washington State University is studying morphological diversity in floral forms, especially in the complex staminal configurations, in the plant family Loasaceae, emphasizing the large genus Mentzelia (blazing stars) and the subfamily Loasoideae. Although a relatively small family in terms of number of species (ca. 325 total), Loasaceae comprise taxa with a wide range of stamen numbers, configurations, and modifications. Taxonomists have used many of these features as characters to recognize distinct genera within the family, but discrepancies with other character evidence have suggested that some of these staminal characters have evolved multiple times, possibly in multiple ways, within Loasaceae, perhaps in association with shifts in pollination. An independent assessment of evolutionary relationships within the family will be made using DNA sequence data collected from nuclear and chloroplast genes, for ca. 114 species and for numerous outgroup taxa in the Hydrangeaceae and other related families. With a robust phylogenetic tree as framework, comparisons can be made between closely related species where the direction of morphological change can reasonably be inferred. Tissue- and organ-level changes in flower development will be studied with light and scanning electron microscopy, to determine whether similar or different patterns of organ formation underlie the various staminal configurations observed in Loasaceae. The study of floral form in Loasaceae represents an early step in the fusion of phylogenetic analysis with morphological transformation. In particular, the study attempts to resolve within Loasaceae what are apparent floral trends in synorganization (unitary growth of formerly separate organs) and juvenilization (early and truncated development that preserves juvenile features as the final "adult" form in the flower).