Taxon Report

Epilobium rigidum Hausskn.

Siskiyou Mountains willowherb

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Taxon Summary

Epilobium rigidum, commonly known as Siskiyou Mountains willowherb, is a perennial herb in the Onagraceae that is found in California and elsewhere. It occurs within Lower montane coniferous forest, growing at elevations from 150 to 1200 meters. Epilobium rigidum is ranked 4.3, Plants of Limited Distribution, A Watch List; Not very threatened in California.

Classification


Scientific Name:	Epilobium rigidum Hausskn.
Common Name:	Siskiyou Mountains willowherb
Family:	Onagraceae
Element Code:	PDONA060V0
USDA Plants Symbol:	EPRI
Synonyms/Other Names:

Ecology and Life History


Lifeform:	perennial herb
Blooming Period: Jul-Aug	Jul-Aug
Elevation:	150-1200 (490-3935)
General Habitats:	Lower montane coniferous forest
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	4.3
Global Rank:	G3G4
State Rank:	S3
State List:	None
Fed List:	None
Other Status:	SB_UCSC
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: False
California Counties and Islands: Name (Code)
Del Norte (DNT), Siskiyou (SIS)
Quads: Name (Quad Code)
Gasquet (4112378), High Divide (4112481), High Plateau Mtn. (4112388), Hiouchi (4112471), Hurdygurdy Butte (4112377), Prescott Mtn. (4112366), Preston Peak (4112375), Shelly Creek Ridge (4112387), Ship Mountain (4112367)

Threat List Data from the CNDDB


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

Notes



On watch list in OR.
Threats:

Taxonomy:

Selected References

Epilobium rigidum profile for potential Species of Conservation Concern evaluation (2018)

Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 16 November 2025].