Persicaria virginiana

About

Persicaria virginiana, also called jumpseed, Virginia knotweed or woodland knotweed is a North American species of smartweed within the buckwheat family. It is unusual as a shade-tolerant member of a mostly sun-loving genus. Jumpseed is a perennial, named for its seeds which can "jump" several feet when a ripe seedpod is disturbed.

Summary from Wikipedia