Taxonomic tools for Salicaceae and Achariaceae
Recent and wide-reaching changes to the taxonomy of Salicaceae, Achariaceae and Flacourtiaceae, based largely on molecular analyses, have proved controversial. This project aims to resolve conflict between different perspectives, stabilize nomenclature within the group and provide World Checklists for the three families involved.
Caloncoba gilgiana. Photo: H. Beentje.
Molecular analyses have led to the breakup of the pantropical family Flacourtiaceae, and movement of its genera into the largely north-temperate Salicaceae and South African Achariaceae, expanding these families out of all traditional recognition and sinking Flacourtiaceae into synonomy under Salicaceae. Over 90 genera and about 1200 species are involved, distributed throughout temperate, tropical and subtropical regions. The taxonomic changes, with supporting non-molecular evidence, were published by Chase et al. in 2002, but are still not universally accepted. The botanical community finds the changes confusing and therefore tends to reject them.
Much of the controversy centres on the genus Oncoba and the genera traditionally grouped with it to form the tribe Oncobeae (now partly the Lindackerieae), for example, Caloncoba and Lindackeria. Two different systems of classification and nomenclature are in current use for this group. One system (Hul & Breteler 1997) relies on morphological characters, the other (Chase et al. 2002) is based on molecular work with supporting morphological and phytochemical evidence. The two different systems are being adopted by different user groups , causing taxonomic confusion and errors in published checklists of critical areas. Field specialists tend to support the Hul & Breteler system, finding it agrees well with their own experience of the group. However Chase et al. (2002) demonstrated that the species of Hul & Breteler's 'Oncoba' , despite being very similar in their floral morphology, are spread across two families: Salicaceae and Achariaceae. The Taxonomic tools for Salicaceae and Achariaceae project aims to further resolve relationships within this difficult group and provide a stable taxonomy.
To promote better understanding of the newly circumscribed Salicaceae and Achariaceae the project will also treat both families for publication in the benchmark reference series by K. Kubitzki: Families and Genera of Vascular Plants (Springer, http://www.springer.com). World Checklists will be provided of both families, that of Salicaceae in collaboration with another Malpighiales Team project : World Classification and Phylogeny of Salix & Populus.
Project partners and collaborators
National Herbarium of the Netherlands, Wageningen University branch
Dept. Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen
Institut für Allgemeine Botanik, Hamburg.