Scientific Name: Polygonum cuspidatum

Common Name: Japanese knotweed

Other Common Names: Japanese bamboo

Synonyms: Fallopia japonica, Pleuropterus cuspidatus, Pleuropterus zuccarinii, Polygonum cuspidatum, var. compactum, Polygonum zuccarinii, Reynoutria japonica

Habit: This erect perennial can grow up to 13 feet in height. It spreads through seeding, and rhizomes.

Leaves: The egg shaped, alternate leaves grow from 4-6 inches in length, and 2-4 inches in width.

Identifying Characteristics: The stems are smooth and swollen at the joints where the leaves grow. The stem above each joint has a thin membranous sheath (ocrea).

Flower Seed Head: Small white flowers grow in clusters from the leaf axils.

Seed Fruit: The seeds are triangular and shiny, and form inside a nutlet.

Where Found: This plant can be found inhabiting areas around streams and rivers. Sunlight, full shade, high salt contents, or drought does not affect this plant.

  • Life cycle: perennial

  • Milky sap: Not Present

  • Plant type: Shrub

  • Thorns: Not Present

  • Plant family: Polygonaceae

  • Leaf arrangement: alternate

  • Leaf shape: oval

  • Ochrea: Present

  • Leaf margin: entire

  • Stem hairs: no hairs

  • Flower color: white

  • Growth habit: upright and nonwoody

  • Stem: round or oval

  • Leaf structure: simple

  • Leaf hairs: no hairs

  • Flower diameter: pencil; dime

  • Flower symmetry: radial symetery

  • Root structure: rhizomes present

  • Leaf stalk: shorter than leaf