Northern Prairie Wildlife Research Center
Northeast Wetland Flora
Field Office Guide to Plant Species
Polygonum densiflorum Meisn.
- Family: Smartweed (Polygonaceae)
- Flowering: August-October
- Field Marks: This smartweed differs by the absence of bristles on the leaf sheaths and the
thickened, crowded spikes of white flowers.
- Habitat: Swamps, wet woods.
- Habit: Perennial herb from thick rhizomes.
- Stems: Spreading to upright, often rooting at the lower nodes, branched, smooth, up to 6 feet tall.
- Leaves: Alternate, simple, lanceolate, pointed at the tip, tapering to the sessile base, smooth on both sides, up to 1 foot long; sheaths without bristles at maturity.
- Flowers: Several in spike-like racemes, the racemes up to 4 inches long, on short-hairy stalks.
- Sepals: 5, united below, white, up to 1/5 inch long.
- Petals: 0.
- Stamens: 6 or 8.
- Pistils: Ovary superior; styles 2.
- Fruits: Achenes lenticular, ovoid, black, about 1/16 inch long.
- Notes: The achenes are eaten by waterfowl.
Previous Species -- Prostrate Knotweed (Polygonum aviculare)
Return to Species List -- Group 8
Next Species -- Marshpepper Smartweed (Polygonum hydropiper)