Pollen morphology and evolution of the genus Harpullia (Sapindaceae—Harpullieae)

The pollen morphology of 20 out of 26 species at present recognised in Harpullia is described. Laminations in the endexine and the presence of a mixed endexine-ectexine layer are demonstrated with TEM sections. Four pollen types, one of which can be subdivided into 8 subtypes, are distinguished and related to each other. The functional morphology and phylogeny of these types is compared with macromorphologic, ecologic and geographic evidence and expressed in a cladogram. The genus probably originated in East Gondwanaland and secondarily invaded Southeast Asia. Its position within Harpullieae is briefly discussed.