The recent discovery of Japanese knotweed (Fallopia japonica) around the parking lot of Marquand Park demands some attention. The perennial has a bamboo-like reddish stem, heart-shaped bright green leaves, and when blooming pretty little white-flower tassels. Introduced in Europe at the beginning of the 19th century, Japanese knotweed became popular as a garden plant because of its soft and pleasing effect. In the United States, Frederic Law Olmsted was responsible for planting it in Central Park.
Over time, the plant has become the most pernicious weed in Great Britain posing a threat to building structures and road surfaces. In the United States, Japanese knotweed is considered an invasive in 38 states and occurs on the New Jersey Invasive Plant Species List. The weed likes to grow along roads and in areas disturbed by human activity. It spreads like wildfire. Eradicating a cluster of plants is not easy. A home improvement website called the Spruce describes techniques such as using tarp to smother the weed; cutting and digging up the plant and its root system; and spraying and injecting knotweed with herbicides. In the United Kingdom, scientists are experimenting with the release of a plant eating insect called Aphalara itadori that feeds on the Japanese knotweed and kills the plant.