• U.S. origins date to the late 1800s, when it was imported from Asia as an ornamental plant.
• One variety, giant knotweed, can grow more than 10 feet tall; its leaves can exceed a foot long.
• Knotweed spreads quickly, crowding out native plants.
• Each flower cluster on a female knotweed plant can produce as many as 1,000 seeds.
• The most successful method of knotweed removal has been a combination of mechanical and chemical methods.
Source: Penn State Extension, www.extension.psu.edu