9408208 Jones Within the last few years, development has emerged as a major theme in evolutionary biology. Recent insights gainsed from interdisciplinary studies of development in animals are laying the foundation for a new synthesis in comparative biology. There have been very few comparable studies in plants, however. The PI will initiate a study of the developmental basis of differentiation in whole plant growth form in the genus Pelargonium. This is an ideal group for this study because 1) species exhibit a tremendous range of whole plant morphology; 2) preliminary analyses of gene sequences suggest that historical relationships can be resolved in this group; and 3) the group is well studied in other respects but basic studies of developmental morphology are lacking. the PI will compare morphological and histological development of seedlings in three species from each major lineage in the subgenus Pelargonium. The proposed investigation focusses on seedlings because this stage of the life cycle represents the earliest expression of the body plan. Structural comparisons of ecologically important structures of seedlings, together with deduction of rules of construction expressed at later stages, will provide the framework for deduction of the whole plant body plan as well as assessment of the importance of the onset and timing of formation of water-storing and carbohydrate-storing tissues.
