September’s weed of the month is giant knotweed (Polygonum sachalinense). Giant knotweed has hollow, bamboo-like stems and grows over 12 feet tall, making it the largest of the invasive knotweeds. It ...

Native to Asia, knotweeds were introduced to North America as an ornamental plant. They can spread into natural areas, grow quickly and form dense monocultures, reducing habitat diversity and ...