Japanese Knotweed

Polygonaceae

LIFE FORM: Perennial

NATIVITY: Asia

VEGETATIVE CHARACTERISTICS:

A fast-growing, rhizomatous plant that forms large clumps over time; individual stems are hollow and jointed, and can reach up to 6 feet in height; broadly, egg-shaped leaves are up to 7 inches long.

FLOWERS:

Conspicuous clusters of white flowers are produced in the leaf axils in late summer; very showy.

FRUIT/DISPERSAL AGENTS:

Spreads primarily by rhizomes and wind-dispersed seeds.

ECOLOGICAL PREFERENCE:

Grows best on moist soil in full sun, but is also shade tolerant. Prefers minimally maintained public parks and open space; abandoned grasslands (meadows); freshwater wetlands, ponds and streams; unmowed highway banks and median strips with frequent salt applications; railroad tracks with ballast substrate.

ENVIRONMENTAL FUNCTION:

Salt tolerance along roadways; erosion control on slopes; stream and river bank stabilization.

CULTURAL SIGNIFICANCE:

Originally introduced as ornamental plant but has escaped cultivation to spread on its own; young shoots are edible with a lemony taste. Invasive species in minimally managed habitats.