Floral ontogenic research provides significant developmental information not seen in mature flowers. Several studies in the Gesneriaceae have previously investigated single or limited numbers of species. In this project developmental processes are being studied at three different taxonomic levels. The first level concentrates on the affinities of the genus Saintpaulia which molecular data suggest has arisen within Streptocarpus subgenus Streptocarpella. The second level investigates the development of the main floral types in Streptocarpus (including Saintpaulia): open tube, keyhole, personate, pouch, dunnii and Saintpaulia type. The third level comprises a more broadly based study including additional genera in the Didymocarpoid Gesneriaceae of Weber's recent classification of the family. The phylogenetic research being carried out on the family (see monographic and phylogenetic research) provides a systematic framework in which to study the floral evolutionary development.
Seed ontogeny studies on Aeschynanthus are completed. A combination of appendage type and seed coat structure is found to be highly informative taxonomically, and will be used to propose a new infrageneric classification. Seed ontogenic studies are continuing on those other genera that possess seed appendages in subfamily Didymocarpoideae, such as Agalmyla, Loxostigma and Lysionotus.
Seeds in genus Streptocarpus in Africa are either verruculose or reticulate, with a tendency of the characteristics to correlate with subgenus Streptocarpella and Streptocarpus, respectively. In Madagascar this correlation breaks down. We are interested in analysing the structural differences during seed ontogeny that leads to these two fundamentally different seed surface sculpture types. This study will address whether the seed ornamentation found in Madagascan species are homologous with those found on the African mainland.
Haston, E & De Craene LP Ronse (2007). Inflorescence and floral development in Streptocarpus and Saintpaulia (Gesneriaceae) with particular reference to the impact of bracteole suppression. Plant Systematics & Evolution 265(1-2): 13-25.
Christie, F. & Mendum, M. (2002). The ontogeny of Aeschynanthus seeds - a comparative study using scanning electron microscopy. Botanical Journal of the Linnean Society 138: 197-207.
Mendum, M., Lassnig, P., Weber, A. & Christie, F. (2001). Testa and seed appendage morphology in Aeschynanthus (Gesneriaceae): phytogeographical patterns and taxonomic implications. Botanical Journal of the Linnean Society 135: 195-213