Cytological analysis of a viviparous onion, known asAllium cepaL. var.viviparum(Metzeg.) Alef., showed that this onion presents a caryogram quite different from the one that characterizesAllium cepa.Moreover, in the viviparous onion, all interphase nuclei have only one nucleolus instead of two, as it is generally inAllium cepa.Data obtained from cytological analysis ofviviparousonion, together with its morphological characteristics, lead to the hypothesis that this line should be considered a clone derived from a more or less remote hybridization betweenAllium cepaandAllium fistulosum.