Polygonum cuspidatum

Japanese Knotweed

Botanical description: Originally introduced to the United States as an ornamental plant, japanese knotweed can now be found nearly everywhere in the city. Tolerant of most habitat conditions, it can colonize riparian sites as well as cracks in asphalt. The plant can negatively impact extant native plant and faunal communities, but in urban conditions, Polygonum cuspidatum is being evaluated for its effectiveness as an accumulator of heavy metals, such as lead, copper and arsenic. Bamboo-like stems can reach a height of ten feet each growing season, emerging from the ground anew after winter dormancy. White flowers form panicles along the stalks at each leaf axis and in terminal clusters. Each flower stalk can produce upwards of 150,000 seeds, dispersed by wind, water and wildlife. Polygonum cuspidatum has an uncanny ability to reproduce itself, whether by seed or its dense network of thick rhizomes that are up to 3” in diameter, any piece of which can form an entirely new plant. Japanese knotweed is also well known to urban foragers, who eat the young tender shoots, similar to asparagus, after they have been boiled. Roots contain an anti-oxidant compound called resveratrol which is being explored for its anti-aging properties.