Taxon Report

Polygonum bidwelliae Wats.

Bidwell's knotweed

Print Report

Taxon Summary

Polygonum bidwelliae, commonly known as Bidwell's knotweed, is a annual herb in the Polygonaceae that is found only in California. It occurs within Chaparral, Cismontane woodland, and Valley and foothill grassland, growing at elevations from 60 to 1200 meters. Polygonum bidwelliae is ranked 4.3, Plants of Limited Distribution, A Watch List; Not very threatened in California.

Classification


Scientific Name:	Polygonum bidwelliae Wats.
Common Name:	Bidwell's knotweed
Family:	Polygonaceae
Element Code:	PDPGN0L0C0
USDA Plants Symbol:	POBI4
Synonyms/Other Names:

Ecology and Life History


Lifeform:	annual herb
Blooming Period: Apr-Jul	Apr-Jul
Elevation:	60-1200 (195-3935)
General Habitats:	Chaparral, Cismontane woodland, Valley and foothill grassland
Microhabitat:	Volcanic
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	4.3
Global Rank:	G4
State Rank:	S4
State List:	None
Fed List:	None
Other Status:
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	0
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	0
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	0

Location


California Endemic: True
California Counties and Islands: Name (Code)
Butte (BUT), Shasta (SHA), Tehama (TEH)
Quads: Name (Quad Code)
Acorn Hollow (4012118), Barkley Mtn. (4012126), Bend (4012232), Burney (4012186), Burney Falls (4112116), Campbell Mound (3912187), Cherokee (3912165), Cohasset (3912186), Dales (4012231), Devils Parade Ground (4012116), Dewitt Peak (4012128), Finley Butte (4012137), Hagaman Gulch (4012157), Inwood (4012158), Los Molinos (4012211), Manton (4012147), Panther Spring (4012127), Paradise East (3912175), Paradise West (3912176), Richardson Springs (3912177), Shippee (3912156), Tuscan Buttes Ne (4012241), Tuscan Springs (4012221)

Threat List Data from the CNDDB


Threat List Total:	0
EOs with Threat Listed:	Total EOs	% of EOs
	0	0 %

Notes



Possibly threatened by vehicles, foot traffic, soil erosion, and non-native plants. See Proceedings of the American Academy of Arts and Sciences 14:294 (1879) for original description.
Threats:

Taxonomy:

Selected References

Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 27 February 2025].