Note on the pollen morphology of Crypteroniaceae s.l

The pollen morphology of the genera Crypteronia, Dactylocladus, Axinandra, Alzatea and Rhynchocalyx is compared in view of a proposal to unite these genera in Crypteroniaceae. Three pollen types are recognized, differing in aperture and shape symmetry, but showing distinct similarities in exine and aperture structure. It is argued that the heterocolpate type found in Dactylocladus, Axinandra, and Rhynchocalyx and the bisyncolporate type characterizing Crypteronia, may both have been derived from a less-specialized tricolpate ancestral type which has been retained in Alzatea. The wider affinities of Crypteroniaceae are discussed and thought to be with Lythraceae and Melastomataceae, although a more remote relationship with Cunoniaceae s also possible.