INTRAINDIVIDUAL VARIATIONS OF CHROMOSOMES AND DNA CONTENT IN MERISTEMS OF ADVENTITIOUS ROOTS OR ORNITHOGALUM-UMBELLATUM L

The 92 bulbs from a population of Ornithogalum umbellatum which is sta ble at 2n = 2x = 18, are characterized by a karyotype containing one p air of large metacentric chromosomes, five pairs of large telocentric chromosomes and three pairs of small submetacentric chromosomes; only, two meristematic root cells of one bulb show aneuploidy (2n = 19 and 2n = 25). Although the mean DNA content measured in metaphase plates o f meristematic cells of adventitious roots from a single bulb is highl y variable (up to 50% difference); in the two cases where aneuploidy w as encountered very little or no increase in DNA content was observed.