Northern Prairie Wildlife Research Center
Cespitose Knotweed (Polygonum cespitosum)
- Family: Smartweed (Polygonaceae)
- Flowering: June-October.
- Field Marks: This species has a smaller stature than
any of the other smartweeds. It also has short, slender spikes
of rose-pink flowers.
- Habitat: Open area in moist soil.
- Habit: Annual herb with fibrous roots.
- Stems: Usually erect, branched or unbranched,
slender, usually smooth, up to 10 inches tall.
- Leaves: Alternate, simple, lanceolate to ovate,
pointed at the tip, tapering to the base, hairy along the edges
and on the veins of the lower surface, without teeth, up to 1 1/2
inches long; sheath with fine bristles at the tip.
- Flowers: Borne in short, cylindrical spikes up to 1
1/2 inches long, rose-pink.
- Sepals: 5, rose-pink, petal-like.
- Petals: 0.
- Stamens: 3-9.
- Pistils: Ovary superior.
- Fruits: Achenes triangular, shiny, up to 1/8 inch
Previous Species -- Scarlet Smartweed (Polygonum amphibium var. coccineum)
Return to Species List -- Group 8
Next Species -- Mild Water Pepper (Polygonum hydropiperoides)