tricolporate, foveolate, distinctly dorso-ventrally flattened, polar view "unmistakable!"

monoporate, pore with distinct annulus; psilate, roundish pollen grain < 40 µm

3 to 4 zonoporate, pore protruding slighty with well-defined annulus; no vestibulum (polar view); round psilate to scabrate pollen grain