Northern Prairie Wildlife Research Center
Pinkweed (Polygonum pensylvanicum)
- Family: Smartweed (Polygonaceae)
- Flowering: July-October.
- Field Marks: Pinkweed differs by the lack of bristles on its leaf sheaths, by its pink flowers, and the short, stiff bristles on the stem just below the cluster of flowers.
- Habitat: Swamps, along streams, around ponds and
lakes, fallow fields, marshes, wet meadows, in ditches.
- Habit: Annual herb with fibrous roots.
- Stems: Erect, smooth or slightly hairy, up to 6 feet tall.
- Leaves: Alternate, simple, lanceolate, pointed at the tip, tapering to the base, without teeth, smooth or with slightly hairy, up to 6 inches long, up to 2 1/4 inches broad, with a sheath not bearing bristles.
- Flowers: Several crowded in racemes up to 1 1/2 inches long; each flower pink, 1/6 inch long, on a stalk that has short, stiff hairs.
- Sepals: Usually 5, pink, united at the base.
- Petals: 0.
- Stamens: Usually 8.
- Pistils: Ovary superior.
- Fruits: Achenes not triangular, black or brown, shiny, 1/6 inch long.
- Notes: The achenes are eaten by waterfowl.
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