Abstract:Using light, transmission and scanning electron microscopy, the development of the pollinium of Goodyera procera (Ker-Gawler) Hooker. was investigated. At the early stage, sporogenous cells inside the microsporangium were seen grouping together into small aggregates each containing few cells. After the aggregates have formed the sporogenous cells inside the aggregates (which could now be called massulae) divide to form numerous pollen mother cells. Later, the pollen mother cells undergo meiosis to form tetrads. The pattern of formation of the exine of tetrads varies according to the location of the tetrads inside the micro- sporangium. Those tetrads that are situated near the outer region of the massulae can form: exine with well developed tectum, bacula and foot layer; and the sequence of events leading to the formation of this type of well developed exine is as follows the original wall and the cyto- plasmic channels associated with the wall become surrounded by a thick layer of callose thus isolating the wall from the plasmalemma. Near the plasmalemma a layer of primexine containing callose and cellulose begins to form. Later, the primexine develops into exine and between the exine and plasmalemma a layer of intine is laid down. Similar type of exine with well developed tectum, bacula and foot layer, is also present in tetrads facing the tapetum. But in this case the original wall of the tedtrad is not retained but undergoes dissolution and in its place a new exine formed. The pattern of formation of exine in the region between tetrads is even more different. Here the original wall also undergoes dissolution but instead of forming a proper exine it only forms a thin foot layer with bulges at places. The pattern of formation of the exine in the cells inside the tetrad is even more different. Here the original wall of the cells only undergoes partial dissolution. The loose fibrils of the partially dissolved wall then become mixed with the callose layer surrounding the cell. Inside this wall-fibril/callose mixture thin sheets of exine appear, but these thin sheets of exine do not develop further into tectum or bacula. In Goodyera a quite substantial amount of callose is retained in the regions between massulae and tetrads, and we believe that it is this callose which is holding the massulae and tetrads together to form pollinium.