Polygonum pensylvanicum

Polygonum pensylvanicum L. of the buckwheat family is also known as Pinkweed, Pink Knotweed, Smartweed, and Pennsylvania Smartweed.^[1]

Pennsylvania smartweed is an erect or sprawling annual, 1 to 5 feet tall. The leaves are lance-shaped and are connected at the node by a membranous sheath, or ocrea. The ocrea is not fringed. The plant flowers July to November. The flowers are rose-pink (or white) and are found in crowded, elongate clusters. Flower stalks often have minute glandular hairs near top, but this is highly variable. The seeds are small, and a shiny brown and encased in achenes. The achenes are elliptical to circular and are a glossy black.

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Cultivation and uses

Pennsylvania smartweed grows in waste ground and crops. It can tolerate many different conditions, but prefers moist soils. It can be found throughout eastern and central North America.

American Indians used tea made from whole plant for diarrhea and poulticed leaves for piles. Bitter leaf tea has been used to stop bleeding from mouth. The tops were used in a tea for epilepsy. Note that the fresh juice is acrid and may cause irritation.

The plant is native to eastern North America. The nectar is useful to insects, the many large seeds to songbirds and wildfowl and the leaves to several kinds of moths and butterflies.

Synonyms

• Persicaria bicornis (Raf.) Nieuwl.
• Persicaria longistyla (Small) Small
• Persicaria mississippiensis (Stanford) Small
• Persicaria pensylvanica (L.) G. Maza
• Persicaria pensylvanica var. dura (Stanford) C.F. Reed
• Polygonum bicorne Raf.
• Polygonum longistylum Small
• Polygonum longistylum var. omissum (Greene) Stanford
• Polygonum mexicanum auct. non Small
• Polygonum mississippiense Stanford
• Polygonum mississippiense var. interius Stanford
• Polygonum pensylvanicum var. durum Stanford
• Polygonum pensylvanicum var. eglandulosum J.C. Myers
• Polygonum pensylvanicum var. genuinum Fern.
• Polygonum pensylvanicum var. laevigatum Fern.
• Polygonum pensylvanicum var. rosiflorum J.B.S. Norton ^[2]

Notes

References

• Richard H. Uva, Joseph C. Neal and Joseph M. Ditomaso, Weeds of The Northeast, (Ithaca, NY: Cornell University Press, 1997), Pp. 280-281.