Systématique du genre Trema en Afrique occidentale.

Abstract

Many species and varieties of the genus Trema have been previously identified in Africa but the wide morphological variation apparently independent of environmental factors has resulted in today's recognition of only one species on the continent, Trema guineensis (syn. T. orientalis). Field observations in Togo and neighboring countries of West Africa confirms this high phenotypic variation but not the asserted lack of segregation within that complex. A numerical taxonomic investigation was carried out to assess the number of taxa present in the area. The results suggest the existence of three distinct groups. Leaf trichome micromorphology and density agree with the existence of those three clusters. Leaf extracts of each group show different activities against one insect and one nematode species but not against a virus. Three species might be recognized in Togo and the neighboring countries: T. orientalis, T. africana and T. nitens. A key to the species is included.