1989 年 54 巻 2 号 p. 355-358
Somatic chromosome numbers were studied from root tips of 18 F1 interspecific hybrids raised from a cross between a male sterile clone of Mentha spicata (2n=72) and a male fertile clone of M.×piperita (2n=120) of the germplasm. The chromosome numbers in the F1 hybrid progeny ranged from 36 to 115. The normally expected chromosome number (2n=96) was found to be the most frequent. Only one hybrid with 2n=36 resembling the female parent (M. spicata, 2n=72) suggested its origin either through female parthenogenesis or normal fertilization followed by selective chromosome elimination. The other hybrid genotypes possessing aneuploid chromosome numbers 2n=110 (13.34%) and 2n=115 (6.67%) possibly arose due to the participation of gametes containing abnormal chromosome numbers produced as a result of misdivision in meiosis of the parental clones.