The pollination mechanisms of Platycladus orientalis (L.) Franco and Thuja occidentalis L. seem to be of the same type, as based on the morphological study of the change in pollination drop, during the process of pollination. Entering the pollination drop, the pollen may alter the surface of the drop or reduce the secretion of the ovule with concomitant increase of evaporation. It has been further noticed that the dynamiechange of the drop withdrawal rate was closely associated with the different kinds of pollen received. It seemsthat the withdrawal of the pollination drop may be induced by pollen from plants consanguineous to P. orientalis, almost as effective as from pollen of P. orientalis itself and comparatively more effective than the foreignpollen received from distant plant species. The drop withdrawal could he mainly induced by the pollen that causes the reduction of ovule secretion.
