TYPES OF CARBOHYDRATE RESERVES IN POLLEN - LOCALIZATION, SYSTEMATIC DISTRIBUTION AND ECOPHYSIOLOGICAL SIGNIFICANCE

Dehiscing pollen grains of 901 species belonging to 104 dicot families and 15 monocot families were scored for starch reserves. Starch grain s showed different physico-chemical properties i.e. colour after iodin e - potassium iodide staining and birefringence or otherwise under pol arized light. Further tests performed in a limited number of species r evealed other kinds of carbohydrate reserves in the cytoplasm but outs ide plastids. From these observations, it results that carbohydrate re serves may be stored in plastids only (amyloplasts), in the cytoplasm but not in plastids, or in both. These kinds of pollen reserves are on ly partly in line with systematics, as only certain families consisten tly show the same type of reserve. These and previous findings suggest that the presence of polysaccharides in the cytoplasm prevents rapid decrease in viability due to desiccation. In this sense, our findings are in line with ecophysiological adaptations such as the respective p ollination syndrome.