Northern Prairie Wildlife Research Center
Water Smartweed (Polygonum amphibium)
- Family: Smartweed (Polygonaceae)
- Flowering: June-August.
- Field Marks: Water smartweed has ovoid spikes less
than 2 inches long, composed of red or pinkish red flowers. The
leaves are usually rounded or heart-shaped at the base.
- Habitat: Marshes, around ponds and lakes.
- Habit: Perennial herb with rhizomes.
- Stems: Erect, branched or unbranched, smooth or
hairy, up to 3 feet tall.
- Leaves: Alternate, simple, broadly lanceolate to
oblong, pointed or rounded at the tip, usually rounded or heart-shaped at the base, without teeth, smooth or hairy, up to 8
inches long, 1 3/4-4 inches broad, with a sheath sometimes
- Sepals: Usually 5, red or pinkish red, united at the
- Petals: 0.
- Stamens: Usually 8.
- Pistils: Ovary superior.
- Fruits: Achenes pale brown, not shiny, not
triangular, 1/10-1/8 inch long.
- Notes: Waterfowl eat the achenes of this plant.
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Return to Species List -- Group 8
Next Species -- Scarlet Smartweed (Polygonum amphibium var. coccineum)