Abstract
In three species of Ranunculus subgenus Batrachium, viz. Ranunculus peltatus Schrank., R. penicillatus (Dumort.) Bab. and R. baudotii Godr., differentiation of antipodals is connected with endomitotic polyploidisation. Calculations of nuclei volume and analysis of nuclei structure were performed in successive developmental stages. Nuclei of the antipodals attained different levels of endopolyploidy: 32n (R. penicillatus), 64n (R. peltatus) and 1024n (R. baudotii), as a maximum. In R. peltaius and R. baudotii, which reproduce sexually, the stimulating effect of fertilization on endomitotic polyploidisatian of the antipodals was found. The occurrence of giant chromosomes in highly endapolyploid nuclei of the antipodals in R. peltatus and baudotii was noted.