Northern Prairie Wildlife Research Center
Mild Water Pepper (Polygonum hydropiperoides)
- Family: Smartweed (Polygonaceae)
- Flowering: July-October.
- Field Marks: This Polygonum differs from all
others by its bristly sheaths, nearly smooth stems, leaves less
than 3/4 inch broad, and non-dotted sepals.
- Habitat: Swamps, along streams, around ponds and
lakes, in ditches.
- Habit: Perennial herb with rhizomes, often forming
- Stems: Erect, usually branched, smooth or slightly
hairy, up to 2 feet long.
- Leaves: Alternate, simple, linear-lanceolate to
lanceolate, pointed at the tip, tapering to the base, without
teeth, smooth or with appressed hairs, up to 4 inches long, less
than 3/4 inch 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 to pinkish, up to 1/4 inch long.
- Sepals: Usually 5, white to pinkish, not black-dotted, united at the base.
- Petals: 0.
- Stamens: Usually 8.
- Pistils: Ovary superior.
- Fruits: Achenes more or less triangular, black or
brown, shiny, about 1/8 inch long.
- Notes: The achenes are eaten by waterfowl.
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