Development of symmetry in flowers and its phylogenetic significance is being investigated and compared among numerous genera in the three subfamilies of Leguminosae. Other aspects being compared include order of initiation of floral organs, onset of aestivation, fusion, and loss of floral organs. With such information one can assess the developmental basis for distinctions between related taxa, and can use this information in phylogenetic analysis. A similar comparative analysis was made among members of the Piperalean families Saururaceae and Piperaceae; the results indicate that these families are specialized, and that their bilateral symmetry in the flowers and unusual origin of flowers isolate the order from other presumed related groups such as Magnoliales. Other areas of research include foliar development in evergreen species, wound regeneration, tendril and spine ontogeny, and intrusive growth of secretory cells. An ongoing survey of lichens of the southeastern United States has resulted in the discovery of many new, poorly known, or infrequently collected species. Ultrastructural studies of tropical crustose lichens under way are revealing new information about phycobiont identity and about haustorial structure.
Tucker, S. C. 1994. Floral ontogeny in Sophoreae (Leguminosae: Papilionoideae), II. Sophora s. 1. (Sophora group). Amer. J. Bot. 81: 368-380.
Murgia, M., B.-Q. Huang, S. C. Tucker, and M. E. Musgrave. 1993. Embryo sac lacking antipodal cells in Arabidopsis thaliana (Brassicaceae). Amer. J. Bot. 80: 824-838.
Tucker, S. C., A. W. Douglas, and H.-X. Liang. 1993. Utility of ontogenetic characters in determining phylogenetic relationships of Saururaceae and Piperaceae. Systematics Bot. 18: 614-641.
Tucker, S. C. 1993. Floral ontogeny of Sophoreae (Leguminosae: Papilionoideae), 1. Myroxylon (Myroxylon group) and Castanospermum (Angylocalyx group). Amer. J. Bot. 80: 65-75.
Tucker, S. C. 1992. The role of floral development in studies of legume evolution. Canad. J. Bot. 70: 692-700.