Size modification of recent pollen grains under different treatments

The effect of various chemicals on the size of recent pollen grains of Corylus avellana L. and Quercus robur L. was studied. The size of acetolysed grains was affected by the treatment prior to acetolysis and moreover by the duration of acetolysis. Preparation methods, which produce comparable sizes and shapes, are given for both fresh and dried polliniferous material. It is concluded that size and shape are valuable for the determination of types. A new method is described for isolating anthers from herbarium sheets without causing great damage to the flower. Glycerin jelly proved to be a good mounting medium, provided that the cover glass is supported by granules of modelling clay.