This publication is the first one of a series concerning the taxonomical. revision of the African Dichapetalaceae.
Of this family the species occur almost exclusively in the tropics of both the old and the new world, but most abundantly in Africa.
In this instalment, the first concerning the genus Dichapetalum,
the gross morphology of the species is extensively treated, and related to the morphological tendencies of the two remaining genera of the family, i.e. Stephanopodium
This proved to be especially important in connection with the systematical position of the Dichapetalaceae,
about which different opinions are held. These different views are mainly caused by differences in the interpretation of the petals and staminodes. It is demonstrated here, that the former should be considered to be staminodes and not proper petals, while the latter are true staminodes and not nectariferous glands.
ENGLER'S conception according to which the family belongs in the order Geraniales is
supported, but not his view concerning close relationship with Euphorbiaceae. Trigoniaceae
and possibly Malpighiaceae
appear to be the close relatives.
The growth mode of the usually lianescent species is closely observed and illustrated. The wide variation between specimens of the same species receives close attention as well. This variability concerns, amongst others, habit, indumentum, inflorescence, and fruit shape.
In the taxonomical part 18 species are described, of which 5 are new, while one is newly combined in Dichapetalum.
The great variability has led in the past to the description of numerous species that have to be reduced into synonymy. This would hardly have been possible without the aid of repeated field observations in Africa, on which occasions ample herbarium material was collected. Apart from the author, several others, mainly staffmembers of the Laboratory for Plant Taxonomy and Plant Geography (WAG) have contributed considerably. Also this fieldwork has added substantially towards a better picture of the distribution of the species.
Specific names as well as synonyms are treated in alphabetical order to facilitate easier access to this work. For the accepted species the most important literature references are given followed by typification and synonyms; the latter are typified and their main literature references are given as well. As the descriptions of the species are rather extensive, the most important characters have been summarized in 'diagnostic characters'. Each species is illustrated in detail and, where useful, a distribution-map is added.
As it will take some time before the revision of the genus Dichapetalum
will be completed, a provisional key to the continental species is appended.