Persicaria barbata

Persicaria barbata, known as bearded knotweed, is a member of the Polygonaceae family. It is native to the Arabian Peninsula and tropical and subtropical Asia, and has been introduced to parts of Africa and the Pacific islands. It grows as an annual herb, 30–60 cm tall, with hairless, line-grooved stems and lance-shaped leaves up to 15 cm long. Some sources describe it as a perennial with robust, loosely branched stems 40–90 cm tall, arising from a creeping rhizomatous rootstock.