Northern Prairie Wildlife Research Center
Bristly Smartweed (Polygonum setaceum)
- Family: Smartweed (Polygonaceae)
- Flowering: July-October.
- Field Marks: The bristly smartweed differs from all other smartweeds by its bristly sheaths, nearly smooth stems, and non-dotted sepals, and from the mild water pepper by its broader leaves, more than 3/4 inch wide.
- Habitat: Wet woods, swamps, around ponds and lakes, in ditches.
- Habit: Perennial herb with rhizomes, often forming mats.
- Stems: Erect or ascending, usually branched, smooth or slightly hairy, up to 2 feet tall.
- Leaves: Alternate, simple, lanceolate, pointed at the tip, tapering to the base, without teeth, smooth or with appressed hairs, up to 6 inches long, 3/4-1 1/2 inches broad, with a sheath bearing bristles at the base of the leaf stalk.
- Flowers: Several crowded in racemes up to 2 inches long; each flower white or pinkish or greenish, up to 1/4 inch long.
- Sepals: Usually 5, white to pinkish to greenish, not black-dotted, united at the base.
- Petals: 0.
- Stamens: Usually 8.
- Pistils: Ovary superior.
- Fruits: Achenes triangular, black, shiny, 1/10 inch long.
- Notes: The achenes are eaten by waterfowl.
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