Abstract
Imperata cylindrica is widely distributed from Okinawa to Hokkaido in Japan, exhibiting great adaptability to various habitats. Recently, we found two types of Imperata cylindrica characterized by flowering phenology in Miyazaki Plain. In this paper, we use isozymes to clarify whether there exist cases of two genetically isolated taxonomic groups of Imperata cylindrica existing in the same area. The flowering periods do not overlap between two types. Got was fixed in each type. Got^b was observed in only E-type (Miyazaki E and Nohbi E), whereas Got^a was observed in only C-type (Miyazaki C, Nohbi C, Miyagi C, Miyakojima C). The D_<ST> of the six populations was 0.254, while the D_<ST> of the two populations of E-type was 0.005, and that of the four populations of C-type was 0.007. Nei's genetic distance among local populations within types ranged from 0.001 to 0.020, while that between two types was 1.29. These results indicate that there are two genetically isolated taxonomic groups with different flowering periods existing in the same area of Japan. Our results accord with the description that the glabrous type corresponds to Imperata cylindrica var. cylindrica (Kenashichigaya), and the node-hair type corresoonds to Imperata cylindrica var. koenigii (Fushigechigaya).
