Abstract
The distribution of the vulnerable plant species Ludwigia peploides ssp. Stipulaceacea was investigated at biyearly from 1998 to 2006, in the Kashio River, eastern Kanagawa. As a result, it was recorded approximately 25-55 local populations. Total cover size were 1,000-1,750 m2 in each year and its averages was about 1,500 m2 (N=5), that is, this species has grown roughly with stability for the investigation period. It was clarified that this species maintained the meta-population shifting position in the river while repeating the formation, the increase and decrease, and the disappearance of the local population by small number of large-scale populations and a lot of small-scale populations. When the relation between the growth size and the river structure of each section was analyzed, it was suggested that the width of the river and existence of the pier positively influence.
