Tapetal Ultrastructural Changes During Pollen Development. II. Studies onPelargonium ZonaleandKalanchoë Obtusa

SUMMARYThe ultrastructure of the tapetal cells was studied in Kalanchoë obtusa and Pelargonium zonale. In an early stage of development the most characteristic feature was the presence of many spherical bodies bounded by a single membrane and containing cytoplasmic material. These bodies were localized in dilations of the ER and in the perinuclear space. In later stages, when the pollen was mature, the tapetal cells of Pelargonium contained many « grey » bodies and their plasmalemma was in close connection with the sculptures of the pollen grains.