Abstract
Resting nuclei, the mitotic prophase and metaphase chromosomes in five species of Lycopus were compared: The resting nuclei were commonly of the complex chromocenter type and the mitotic prophase chromosomes were of the proximal type. Lycopus ramosissimus, L. maackianus, L. unifloru and L. europaeus showed commonly the chromosome number of 2n=22, while L. lucidus showed 2n=66. The chromosome number of 2n=66 in L. lucidus and that of 2n=22 in L. ramosissimus were reported here for the first time, and that of 2n=22 in L. maackianus, L. uniflorus and L. europaeus verified the previous reports. Four species of the genus with 2n=22 could be all diploid and one species with 2n=66 could be hexaploid if the basic chromosome numbers x=11 was accepted.
