Pale Smartweed, dockleaf smartweed, nodding smartweed, curltop ladysthumb, curlytop knotweed
Description: summer annual
Place of origin: eastern North America and Europe
Urban habitat: commonly found along roadsides, stone walls, in floodplains, waste areas, vacant lots, in compacted soil near wetlands, and in poorly drained lawns and cultivated fields.
Ecological function: disturbance-adapted colonizer of bare ground; food and habitat for wildlife.
History: Several Native American tribes used Polygonum lapathifolium medicinally for treatment of stomach ailments, hemorrhoids, diarrhea, and fever. The Navajo used an infusion of the plant as a ceremonial lotion. The whole plant is antiseptic and astringent and produces a white forth that has been used as soap for bathing and washing clothes. Its young leaves and seeds can be consumed raw or cooked. Some members of this genus can cause photosensitivity in susceptible people.