XVI International Botanical Congess

The chromosomal locations of 18S and 5S rDNA in the three species of Cyperaceae were determined by fluorescens in situ hybridization. In Eleocharis mamillata var. cyclocarpa(2n=16), 18S rDNA loci occur at 12 sites of terminal regions. Two small chromosomes have 18S rDNA loci at both ends. The 18S rDNA loci of Carex pachgyna (2n=12) and Carex ciliato-marginata(2n=12) occur at the terminal regions. The 5S rDNA loci of E. mamillata var. cyclocarpa occur at interstitial regions of two small chromosomes. In C. pachgyna and C. ciliato-marginata, 5S rDNA loci are localized at terminal or interstitial regions of two medium chromosomes. Although the chromosomes of Cyperaceae posses non-localized centromere, the 18S and 5S rDNA loci are localized at the terminal or interstitial regions. These results show the rDNA loci in Cyperaceae are quite comparable to the chromosomes with localized centromere of higher plants.