The object of this study was to morphologically characterise the pollen grains from species endemic to the Azores, Portugal, in order to devise a pollen key to identify this plant group. The pollen grains from each studied species were subjected to standard acetolysis, and were mounted on at least three permanent slides for each species, in order to observe and measure the pollen grains. Pollen surface details were described from images obtained through a scanning electron microscope. A total of 43 endemic species, distributed in 22 families and 37 genera, were analysed. It was observed that most of the studied families showed specific traits of polarity, sexine ornamentation, absence or presence of aperture and shape, and can be considered eurypalynous. Families Apiaceae, Ericaceae and Poaceae showed stenopalynous traits among species. The results obtained in this work made it possible to devise a pollen key to identify of the studied species.