The identification of pollen is widely used in the reconstruction of vegetation, the climate of the past, and plant biodiversity. Studies concerning pollen structure, size, and form are key issues in basic sciences as plant taxonomy and evolution. But they also play an important role in applied fields as plant breeding. In pollination studies pollen is generally used to identify food sources of visitors and to reconstruct their foraging routes. The 16 papers in this volume consider the functional ecology of pollen in relation to its structure and constituents as a framework towards a better understanding of evolutionary processes that mold pollination biology. They can be roughly classified into three main topics: pollen structure and constituents, pollen evolutionary ecology, and the pollen-pollinator interface. Floral reward, such as pollen and nectar, are only one aspect of the multidimensional pollination caleidoscope. Other aspects include the various mechanisms in distributing or collecting pollen, the question of pollen longevity, or the convergence of evolution in angiosperm pollination.