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Synonyms: Fallopia sachalinensis (F.Schmidt) Ronse Decr. APNI*
Polygonum sachalinense Schmidt APNI*
Tiniaria sachalinensis APNI*

Description: Perennials 2–5 m high, forming a dense thicket; very strongly rhizomatous. Stems annual, robust, bamboo-like, green, numerous and branched above, dying back in winter.

Leaves ovate to more or less oblong, 15–40 cm long, 7–25 cm wide, with scattered or more or less dense long multicellular flexuose hairs on the abaxial surface, and the apex more or less acute, the base deeply cordate.

Flowers in clusters of 4–7, in paniculate inflorescences with rather stout, dense branches; perianth segments pale green to creamy-white, the outer 3 developing broad wings at maturity.

Achene 2–3 mm long, glossy, brown.

Herbarium Sheet

Distribution and occurrence: Cultivated in gardens, occasionally persistent on old garden sites or naturalised in temperate areas of SE Australia (Penrose, Tidbinbilla - possibly eradicated there; Victoria). Native of Korea, Japan, Taiwan and eastern China. Cultivated in Europe and North America but now considered a problem weed there. Hybridizes readily with R. japonica; the hybrid is known as R. x bohemica.

Cool climate, moist, open sites such as stream banks or roadsides.
NSW subdivisions: *CT, *ST
Other Australian states: *Vic.

AVH map***

Previously treated as Fallopia sachalinensis. It hybridises with R. japonica, and that hybrid (R. x bohemica is also in Australia. These giant knotweeds are potentially serious weeds in cooler climate regions of Australia.