Pollen morphology of Diosma and Coleonema (Rutaceae : Diosminae) and its taxonomic implications

The pollen morphology of Diosma and Coleonema of the taxonomically problema tic subtribe Diosminae (Rutaceae) was investigated to determine its taxonom ic relevance. Pollen of 26 of the 28 species of Diosma and of each of the e ight species of Coleonema was investigated by LM, SEM and TEM. In pollen of Diosma the exine sculpturing is uniform, and only one pollen type, reticul ate, could be distinguished. In contrast, exine sculpturing shows interspec ific variation in Coleonema and three distinct types, striate, reticulate a nd perforate, could he discerned. Species groupings indicated by the pollen types suggest possible relationships between species within Coleonema and with other genera that were not previously apparent. Pollen data support ma cromorphological evidence that suggests the generic re-classification of th e Diosminae.