A PRELIMINARY CLASSIFICATION OF EUPHORBIA SUBGENUS EUPHORBIA

During preparation of the Euphorbieae for the Flora of Tropical East A frica, most of the 250 plus species in Euphorbia subg. Euphorbia were examined, resulting in a new approach to their classification. Comment s are offered on the principal systems to date, all of which have been based on vegetative characters. In the newly proposed system, certain character changes linked with increasing succulence and a reduction i n size are used to indicate development from trees, to shrubs, and the n herbs, as an advancement in adaptation toward survival in arid condi tions. Features of the inflorescence, capsules, and seeds are consider ed to be the most important in deciding relationships between groups, while vegetative features are used as indicators of development within the groups. A system of two sections based on seed characters is prop osed, and the relationships between eight proposed subsections are dis cussed.