E-Flora BC: Electronic Atlas of the Flora of British Columbia

Reynoutria sachalinensis (F. Schmidt ) Ronse Decraene
giant knotweed
Polygonaceae (Buckwheat family)

Introduction to Vascular Plants

© Adolf Ceska  Email the photographer   (Photo ID #20526)

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Distribution of Reynoutria sachalinensis
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Species Information

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Perennial herb from a rhizome; stems erect, numerous, branched, 2-4 m tall, reddish, hollow.
Basal leaves lacking; stem leaves alternate, 10-30 cm long, the blades widely egg-shaped, the bases heart-shaped, the tips gradually tapered, long stalked; stipules tubular, entire.
Flowers in small axillary panicles; perianths 2-3 mm long, pale green or greenish-white, unequally 5-lobed, the outer lobes strongly winged.
Achenes, 3-angled, about 3 mm long, black, smooth and shiny.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Mesic fields, roadsides and waste places in the lowland zone; infrequent on Vancouver Island, the Gulf Islands and the Vancouver area, rare on the midcoast (Prince Rupert); introduced from Asia.

Source: The Illustrated Flora of British Columbia

Synonyms and Alternate Names

Fallopia sachalinensis

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References