THE PROCESSES OF ANTHER DEHISCENCE AND POLLEN DISPERSAL: II. THE FORMATION AND THE TRANSFER MECHANISM OF POLLENKITT,...

The development of the locule of Gasteria verrucosa (Mill.) H. Duval and Lilium hybrida cv. Enchantment, especially the border between the sporophyte and the gametophyte, is investigated by means of light and electron microscopy, histochemistry and micromanipulation and related to pollen dispersal. The pecto-cellulosic cell walls of both the middle layer and the tapetum and a part of the endothecium disappear, and the tapetum cells are covered with sporopollenin-containing tapetal membranes and orbicules. The cell contents of the tapetum turn into the hydrophobic pollenkitt. In the locule, similar changes are observed as the pecto-cellulosic and callose walls of the meiocytes disappear and the future pollen grains are covered with the sporopollenin-containing exine. Due to their non-wettability, these hydrophobic substances on both sides of the sporophyte-gametophyte surface are important in pollen dispersal. The transfer of pollenkitt from the tapetum to the locule appears to be due to capillary forces in the locule after the continuous expansion of the pollen, rather than to active flow or to direct attraction by the pollen grains.