Calflora
Taxon  Report   11035    
Polygonum majus  (Meisn.) Piper
Large douglas' knotweed
Polygonum majus
© 2008 Keir Morse
Photos from
CalPhotos / Calflora
Polygonum majus
© 2008 Keir Morse
Polygonum majus
© 2009 Neal Kramer
Polygonum majus, a dicot, is an annual herb that is native to California, is also found outside of California, but is confined to western North America.

Interactive Distribution Map


Observation Hotline
(observation details)



point, line, or polygon

Plant Characteristics
and Associations



Bloom Period
Polygonum majus
© 2008 Keir Morse
Family: POLYGONACEAE  
Genus: Polygonum
Wetlands: Occurs usually in non wetlands, occasionally in wetlands

Serpentine affinity: 1.5; (weak indicator)

Name Status:
Accepted by JEF

PLANTS accepted name:
Polygonum douglasii ssp. majus

Alternate Names:
ICPN: Polygonum douglasii ssp. majus
More information about  Polygonum majus
Nursery / seed vendor availability from CNPLX
Commercial availability unknown.
Landscaping information from Calscape
Photos on PlantID.net   /   Google Images
Jepson eFlora

Records from the Consortium of California Herbaria

USDA PLANTS Profile (PODOM2)

Search efloras.org (Flora of North America)

website references from Google


Suggested Citation
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. [web application]. 2019. Berkeley, California: The Calflora Database [a non-profit organization]. Available: https://www.calflora.org/   (Accessed: Jan 20, 2019).