Reynoutria japonica (Houtt.) Ronse Decr. var. japonica
Japanese knotweed
Polygonaceae (Buckwheat family)
Introduction to Vascular Plants
Japanese knotweed
Polygonaceae (Buckwheat family)
Introduction to Vascular Plants
Map
Distribution of Reynoutria japonica var. japonica
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Species Information
General:
Perennial herb from a rhizome; stems erect, numerous, branched, 1-3 m tall, reddish-brown.
Leaves:
Basal leaves lacking; stem leaves alternate, 10-15 cm long, the blades egg-shaped to more or less round, the bases rounded or squared off, the tips abruptly pointed, long stalked; stipules short, tubular, entire, usually deciduous.
Flowers:
Inflorescence of numerous flowers in many panicles; perianths whitish or greenish-white, about 2 mm long at anthesis, 5-lobed nearly to the base.
Fruits:
Achenes, 3-angled, black, smooth and shiny, 2.5-3 mm long.
Notes:
Easily confused with P. sachalinense.
Habitat and Range
Moist to mesic ditches and disturbed sites in the lowland zone; frequent in the lower Fraser Valley, rare in the Queen Charlotte Islands, Powell River and SC BC; introduced from Asia.Status Information
Synonyms
Synonyms and Alternate Names:
Fallopia japonica