Polygonum cuspidatum Siebold & Zucc.

Japanese knotweed, Mexican bamboo

Two similar knotweeds

	Polygonum sachalinense	You are here Polygonum cuspidatum
Common Name	giant knotweed	Japanese knotweed
Plant	Stems are hollow, and thickly clustered, closely resembling bamboo. Plants are large, up to 13′ (4 m) in height.	Japanese knotweed stems are jointed and hollow like bamboo. Plants reach up to 12′ (3.7 m), but are usually half that.
Leaves	Alternate, ovate (oval, wider at the bottom), cordate (heart-shaped), up to 1′ (30 cm) long, with crenate (wavy) edges.	Leaves are oval, wider and flat near the base, 2–6″ (5–15 cm) long and 1–4″ (2.5–10 cm) wide.
Flowers	Groups of slender cone-shaped panicles, white or greenish in color.	In multiple upward pointing spikes containing many tiny white to pale yellow flowers.
Fruit	Triangular, with three "wings."	Seed pods are shaped like inverted hearts, about ⅛″ (3.2 mm) long.
Range/ Zones	USDA Zones: 5-8
Habitats	Rivers, swamps, and other wetland regions.	Wet areas and disturbed areas

Polygonum cuspidatum description by Thomas H. Kent, not updated.

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