Trithuria sect. Hamannia is a section within the genus Trithuria native to Australia and India.Sokoloff, D. D., Remizowa, M. V., Macfarlane, T. D., Conran, J. G., Yadav, S. R., & Rudall, P. J. (2013). Comparative fruit structure in Hydatellaceae (Nymphaeales) reveals specialized pericarp dehiscence in some early–divergent angiosperms with ascidiate carpels. Taxon, 62(1), 40-61.
Description
The dehiscent, elliptical, apocarpous, monomerous follicle fruitRomanov, M. S., Bobrov, A. V. C., Iovlev, P. S., Roslov, M. S., Zdravchev, N. S., Sorokin, A. N., ... & Kandidov, M. V. (2024). Fruit and seed structure in the ANA‐grade angiosperms: Ancestral traits and specializations. American Journal of Botany, 111(1), e16264. has three longitudinal pericarp ribs. The fruit does not have papillae, doesn't have distinct epicuticular wax deposits, and the apex does not have thickened endocarp cells. The fruit apex also does not have a distinct beak. The fruit splits into three parts along the longitudinal ribs. The smooth seed has a thick cuticle. The sheathless cotyledon is strongly reduced.
Taxonomy It was described by Dmitry Dmitrievich Sokoloff, William J. D. Iles, Paula J. Rudall, and Sean W. Graham in 2012 with Trithuria lanterna as the type species.Iles, W. J., Rudall, P. J., Sokoloff, D. D., Remizowa, M. V., Macfarlane, T. D., Logacheva, M. D., & Graham, S. W. (2012). Molecular phylogenetics of Hydatellaceae (Nymphaeales): Sexual‐system homoplasy and a new sectional classification. American Journal of Botany, 99(4), 663-676. Species It has three species:Iles, W. J. D. (2013). The Phylogeny and Evolution of Two Ancient Lineages of Aquatic Plants (Doctoral dissertation, University of British Columbia).
Trithuria polybracteata Trithuria konkanensis Trithuria lanterna
Etymology The section name Hamannia honours Ulrich Hamann who worked on and described the family Hydatellaceae.Hamann, U. (1976). Hydatellaceae—a new family of Monocotyledoneae. New Zealand Journal of Botany, 14(2), 193-196. Distribution Its species occur in India (Western Ghats) and Australia (tropical Western Australia, tropical northern Australia).
Phylogeny Trithuria sect. Hamannia split from Trithuria sect. Altofinia about 6 million years ago in the Upper Miocene.Lin, Q. (2014). Using a low-copy nuclear gene (phosphoglycerate kinase; PGK) to explore the phylogeny of the aquatic plant family Hydatellaceae (Nymphaeales) (Doctoral dissertation, University of British Columbia).
References