Citrus chimeras NFF (layer constitution:L1-L2-L3=NFF) and FNN (layer constitutionL1-L2-L3=FNN) were periclinal chimeras, produced by grafting of Citrus sinensis cv. Fukuhara orange (F) and C. natsudaiddai cv. Kawano natsudaidai(N). Some characters of F or N, such as the color of epicarp and juice sacs of fruits, developed independently in their chimeras, while other characteristics, including leaf size and stoma size, sugar content, acidity and size of the fruits in the chimeras displayed interactions between the two genetically different tissues, i.e., the `exogenous' epidermis (L1) in the chimeras imposed effect on the quantitative characters that were inner tissue derived or determined of making them oriented to those of its (L1) donor plant. So did the inner tissues to the L1-determined or derived traits. Cell displacement occurred during leaf development in the NFF chimera and cell replacement in both chimeras occurred during fruit development. Peroxidase analysis revealed that each donor plant had one unique band. The N-peroxidase band was stably detected in both chimeras. This band could thus be used as a reliable marker of N tissue in chimeric plants. No chimera specific isozyme band was detected. RAPD analysis, however, showed the presence of chimera specific bands besides the donor specific bands. This suggests that interactions between genotypically different cells caused variation(s) at the DNA level, and thus could be a source of genetic variation(s).