Cold-induced decondensation of heterochromatic regions (CSR-bands) in Paris hainanensis (=Daiswa hainanensis Merrill Takht.) (2n = 10; 10 + b) was studied. The comparison of CSR-banding patterns with those obtained by nucleotide-specific staining with fluorochromes DAPI and chromomycin A₃ demonstrated that low temperatures induced decondensation only of large AT-rich heterochromatic regions. It is suggested that this is characteristic of all plant species.