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Taxon  Report  
Fallopia sachalinensis  (F. Schmidt Petrop.) Ronse Decr.
Giant knotweed
Fallopia sachalinensis is a perennial herb that is not native to California.
Cal-IPC rating: moderate
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Observation Search
~143 records in California
redone or more occurrences
within a 7.5-minute quadrangle

Bloom Period
Genus: Fallopia
Family: Polygonaceae  
Category: angiosperm  
PLANTS group:Dicot
Jepson eFlora section: eudicot

Wetlands: Occurs usually in non wetlands, occasionally in wetlands

Communities: escaped cultivar

Name Status:
Accepted by JEF

Alternate Names:
JEFPolygonum sachalinense
JEFReynoutria sachalinensis
JEFTiniaria sachalinensis
PLANTSPolygonum sachalinense
Information about  Fallopia sachalinensis from other sources

[Wikipedia] Northern Japan & far east Russian native, Description: Reynoutria sachalinensis (giant knotweed or Sakhalin knotweed syns. Polygonum sachalinense, Fallopia sachalinensis) is a species of Fallopia native to northeastern Asia in northern Japan (Hokkaido, Honshu) and the far east of Russia (Sakhalin and the southern Kurile Islands).[2] Stem and inflorescence Reynoutria sachalinensis is a herbaceous perennial plant growing to 2 to 4 m (79 to 157 in) tall, with strong, extensively spreading rhizomes forming large clonal colonies. The leaves are some of the largest in the family, up to 15 to 40 cm (6 to 15.5 in) long and 10 to 28 cm (4 to 11 in) broad, nearly heart-shaped, with a somewhat wavy, crenate margin. The flowers are small, produced on short, dense panicles up to 10 cm (4 in) long in late summer or early autumn; it is gynodioecious, with male and female (male sterile) flowers on separate plants. The species is closely related to the Japanese knotweed, Reynoutria japonica, and can be distinguished from it by its larger size, and in its leaves having a heart-shaped (not straight) base and a crenate margin. Reynoutria sachalinensis has a chromosome count of 2n=44.[3][4] (contributed by Mary Ann Machi)

Suggested Citation
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals. [web application]. 2024. Berkeley, California: The Calflora Database [a non-profit organization]. Available: https://www.calflora.org/   (Accessed: 04/12/2024).