Species Details

Polygonum marinense

Marin knotweed

Download Report Calflora eFlora CCH CalPhotos

Classification

Scientific Name: Polygonum marinense Mertens & Raven
Common Name: Marin knotweed
Family:	Polygonaceae
Element Code:	PDPGN0L1C0
USDA Plants Symbol:	POMA15
Synonyms/Other Names:

Conservation Status

CA Rare Plant Rank:	3.1
Fed List:	None
State List:	None
Global Rank:	G2Q
State Rank:	S2
Other Status:
CRPR Changes: changed from 3.1 to 3.1 on 2008-07-14
Add Date:	1974-01-01
Date Edited:	2021-05-26

Ecology and Life History

Lifeform: annual herb

Blooming Period: (Apr)May-Aug(Oct)

Elevation:
0 - 10 meters
0 - 35 feet

General Habitats:

Marshes and swamps (brackish, coastal salt)

Microhabitat Details:

Microhabitat:

Notes

Notes: Move to List 1B? Known from fewer than twenty occurrences. Taxonomic status uncertain, related to P. aviculare; possibly synonym of P. robertii, a non-native plant. Immediate taxonomic study needed. Threatened by coastal development and foot traffic.
Threats:
Taxonomy:

Threat List Data from the CNDDB

THREAT LIST:
Threat List Total:	9
	Total EOs	% of EOs
EOs with Threat Listed:	17	53 %
Grazing	14	43%
Foot traffic/trampling	9	28%
Altered flood/tidal/hydrologic regime	2	6%
Development	1	3%
Erosion/runoff	1	3%
Non-native plant impacts	1	3%
Other	1	3%
Recreational use (non-ORV)	1	3%
Vandalism/dumping/litter	1	3%

Occurrence Data from the CNDDB

Element Occurrence Ranks:
Total Occurrences:					32
A	B	C	D	X	U
2	13	9	0	0	8

Occurrence Status:
Historical >20 Years	27
Recent <=20 Years	5

Presence:
Presumed Extant	32
Possibly Extirpated	0
Presumed Extirpated	0

Location

California Endemic:

California Island:

States: Name (Code)
California (CA)

California Counties and Islands: Name (Code)
Alameda (ALA), Contra Costa (CCA), Marin (MRN), Napa (NAP), San Francisco (SFO), Solano (SOL), Sonoma (SON)

Quads: Name (Quad Code)
Benicia (3812212), Bodega Head (3812331), Cuttings Wharf (3812223), Drakes Bay (3812218), Hunters Point (3712263), Inverness (3812217), Oakland East (3712272), Oakland West (3712273), Petaluma Point (3812214), Petaluma River (3812225), San Leandro (3712262), San Rafael (3712285), Tomales (3812228)

Notes:

Definitions of codes following a county and/or quad:
*		Presumed extirpated
(?)		Occurrence confirmed, but possibly extirpated
Quad and county data is imported from the CNDDB. Species may be present in other areas where conditions are favorable. These data should NOT be substituted for pre-project review or for on-site surveys.

Regional Map

Map

Presumed Extant

Click on quad for name. Hold Shift Key to use mouse scroll wheel

Selected References

CNPS Status Review:

CRPR List Change on 2008-07-14