Polygonum

Polygonum features somewhat prominently in the denouement of the Miss Marple mystery Nemesis.

Knotweed
Polygonum is a genus of about 130 species of flowering plant in the buckwheat and knotweed family Polygoneceae. Common names include knotweed and knotgrass. In the Middle English glossary of herbs Alphita (c. 1400–1425), it was known as ars-smerte. There have been various opinions about how broadly the genus should be defined. For example, buckwheat (Fagopyrum esculentum) has sometimes been included in the genus as Polygonum fagopyrum. Former genera such as Polygonella have been subsumed into Polygonum; other genera have been split off.

Polygonum produces several varieties which grow, or overgrow, in herbaceous borders or as climbers.

Traditional Medicine uses
Polygonum multiflorum (Fo-ti) is a popular herb in traditional Chinese medicine. Folks have used it to relieve insomnia, combat diabetes, stimulate hair growth, and more.