Calflora
Taxon  Report   11035    
Polygonum majus  (Meisn.) Piper
Large douglas' knotweed
Polygonum majus
© 2008 Keir Morse
Photos from
CalPhotos / Calflora
Polygonum majus
© 2009 Neal Kramer
Polygonum majus
© 2008 Keir Morse
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 + photos)



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]. 2018. Berkeley, California: The Calflora Database [a non-profit organization].
Available: https://www.calflora.org/   (Accessed: Nov 14, 2018).

The information on this page comes from diverse sources. None of the links are sponsored.