Persicaria posumbu

Persicaria posumbu is a species of flowering plant in the family Polygonaceae. It was first described as "Polygonum posumbu" in 1825 and transferred to the genus "Persicaria" in 1919. Plants of the World Online records it as having a discontinuous native distribution: , Bangladesh and the eastern Himalayas to the west, and Japan, Korea, the Kuril Islands and Primorye to the east.
There is some confusion over the relationship between "Persicaria posumbu" and "Persicaria cespitosa". Some sources regard "P. cespitosa" as an independent species, others regard "P. cespitosa" as a synonym of "P. posumbu".