About 130 species of Knotweed or Smartweed are known, and most are plants of disturbed, moist areas. They vary greatly, can be annuals or perennials, and are mostly found in northern temperate areas of the world. Most are considered weedy. Native varieties tend to grow partially immersed in shallow waters of marshes, swamps, wet forests or ditches. The small flowers are generally in terminal spikes. P . pensylvanicum and P. punctatum var. punctatum are native to North Carolina.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.