Abstract

The anatomy and some submicroscopic cellular structures in the root cap of developing adventitious root of Ceratopteris thalictroides were studied. The root cap initial originates from the single apical cell in the root meristem by means of sequencial segmentation. The root cap initial then follows an orderly cell division to give rise to a multicellular root cap since the cap cells are traceable to their common origin or to the apical cell. The cap cells increase consiclerably in size as they develop. During the course of cap cell development, the nucleus is still present with little increase in size and the nucleolus appears to be absent in older root cap cell. Most of the cytopjasmic organelles maintain rather complete figures even in the sloughing off cells except the plastids. The possible significance of wall structure in relation to the process of sloughing off is discucussed. The root cap shows characteristic features which lead to the consideration that the root cap may be an acting or modified multiseriate epidermis.