Descriptions are given of the tetrad of Drimys winteri, Winteraceae, as revealed by light and electron microscopy. It is shown that the thickness and appearance of the layers of the sporoderm vary considerably in the different areas of the pollen grain. There is neither fusion nor direct contact between the walls of the four monads; the cohesion of the tetrad is ensured by some internal baculae alone. The calymmate tetrad of Victoria cruziana, Nymphoeaceae, is compared with this acalymmate tetrad