Plasmodesmata mediate the exchange of information in the form of miRNA, proteins and mRNA between adjacent cells in the course of plant development. This fundamental role of plasmodesmata is well established in angiosperms but has not yet been traced back to the evolutionary ancient plant taxa. Comparative studies on representatives of such taxa including gymnosperms, ferns and lycophytes could shed light on the origin and development on non-cell autonomous regulation of gene expression in plants. The KNOX genes, coding for non-cell-autonoumous homeodomain transcription factors that function as regulators of apical meristems, have been characterized in a large number of angiosperms, and also in some representatives of other taxa. Therefore, the KNOX proteins can be used as models for characterization of cell-to-cell transport. To this end, the patterns of localization of KNOX transcripts, KNOX proteins and of plasmodesmata, respectively, need to be compared in the meristems of the representatives of different