Knotweed (Persicaria), fam. Polygonaceae.
The Persicaria genus has been recently separated from the Polygonum species (exampled as a common knotweed). The possible variants of our species are: Pale Smartweed (Persicaria lapathifolia), Lady's thumb (P. maculosa).
Occurs in the forest, mostly aside the lakes. Used as diuretic, laxative, and against hemorrhoids.
In the city, it is sometimes possible to meet the tall (1-2 m height) Prince's Feather (Persicaria orientalis).