Ten genera and seventeen species of Apocynaceae from Taiwan were studied by means of transmission electron microscopy. Five types of exine stratification are recognized based on ultrastructural features and apparent chemical characteristics. In type I, the nexine corresponds to a foot layer plus the endexine; in type II, the nexine corresponds directly to the foot layer only; in type III, the nexine corresponds directly to the endexine only; in type IV, the nexine is absent and the infratectal stratum is a granular layer and in type V, the nexine is also absent, but the infratectal stratum is a reticular layer at upper and lower portions underlain by a granular layer in the middle with granules of varying size and shape. Except for the species ofTrachelospermum, the rest of the infrageneric taxa can be keyed out by palynological characters. Possible evolutionary trends in exine stratification are proposed.