Formation and development of the tapetal periplasmodium inTradescantia bracteata

Summary The formation of the tapetal periplasmodium inTradescantia bracteata is described at the electron microscope level and methods are given for the preparation of material. Evidence, both fine-structural and cytochemical, is presented in support of the view that the tapetal periplasmodium inTradescantia posesses an organized, functional ultrastructure. The changes which occur after dissolution of the tapetal walls appear to be a reorganization rather than a degeneration. The observation that tapetal membranes penetrate the exine during the later stages of pollen development suggests that a physical association may develop between the cytoplasm of the male gametophyte and that of the sporophyte.