Pollen morphology of the genus Lepisanthes (Sapindaceae) in relation to its taxonomy

The pollen morphology of 18 out of 22 species of the genus Lepisanthes, as recently revised, was studied. General pollen morphology is rather uniform, but taxonomically significant differences exist in shape, relative length of ektoapertures, endoaperture development, and in the sculpture of the tectum. Detailed descriptions are presented and special attention is given to intraspecific variability. 10 Pollen types are recognized, most of which are linked by transitions. Morphological trends are established and the extent to which they indicate natural relationships is evaluated. In subgenera Lepisanthes and Erioglossum a less evolved but more variable pollen morphology is present, while in subgenera Otophora and Aphania derived pollen types occur, which agrees well with macromorphological evidence. Subgenus Erioglossum appears pollenmorphologically closely related to subgenus Lepisanthes. Subgenus Aphania can, both macro- and pollenmorphologically, be derived from subgenus Otophora. Within Lepisanthes tetraphylla close parallels exist between macromorphological and palynological interpretations of natural affinities between the numerous races. Lepisanthes fruticosa, in contrast, shows on both counts rather wide and continuous intraspecific variability. Also in Lepisanthes senegalensis continuous pollenmorphological variability is present, but here a clinal pattern can be detected. In general, geographically isolated or endemic forms in Lepisanthes show a tendency to develop deviating pollen types.