Polygonum argyrocoleon

Polygonum argyrocoleon, common names silver-sheath knotweed and Persian knotweed, is an Asian species of plants in the buckwheat family. It is native to Siberia, western China, Central Asia, and the Middle East. It has also become naturalized in parts of the United States, primarily the Southwest, and northwestern Mexico.
"Polygonum argyrocoleon" is an annual herb up to tall. It has very small leaves rarely more than long.