Home/Species/ Oregon Willowherb

Epilobium oreganum

Greene

Oregon Willowherb

G3Vulnerable Found in 2 roadless areas NatureServe Explorer →

G3VulnerableGlobal Rank

HighThreat Impact

Identity

Unique IDELEMENT_GLOBAL.2.158466

Element CodePDONA060P0

Record TypeSPECIES

ClassificationSpecies

Classification StatusStandard

Name CategoryVascular Plant

Endemicendemic to a single nation

KingdomPlantae

PhylumAnthophyta

ClassDicotyledoneae

OrderMyrtales

FamilyOnagraceae

GenusEpilobium

Concept Reference

Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

Conservation Status

Rank Method Rank calculation - Biotics v2

Review Date2025-12-30

Change Date2025-12-30

Edition Date2025-12-30

Edition AuthorsTomaino, A.; R. Bittman (2009), rev. C. Nordman (2025).

Threat ImpactHigh

Range Extent5000-20,000 square km (about 2000-8000 square miles)

Number of Occurrences21 - 80

Rank Reasons

Oregon Willowherb (Epilobium oreganum) is a wetland plant known only from serpentine fens and streamsides in northern California and extreme southwestern Oregon. It is estimated that there are between 21 and 80 occurrences rangewide, and the total population size is about 15,000 plants. It is threatened by mining activities, wetland alteration and drainage, fire suppression, off-road vehicles, logging, and grazing. Monitoring existing populations is important to improve our understanding of reproduction, plant abundance, threats, and trends, and the effectiveness of conservation measures.

Range Extent Comments

Oregon Willowherb (Epilobium oreganum) occurs in the Siskiyou Mountain area in Josephine County, in southwestern Oregon and mountainous areas of northwestern California, mostly in Trinity County but also in adjacent Humboldt, Shasta, and Tehama counties (FNA 2021). Range extent was estimated to be 13,958 square kilometers, using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1994 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).

Occurrences Comments

By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are between 21 and 80 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).

Threat Impact Comments

This species is threatened by mining activities, wetland alteration and drainage, fire suppression, off-road vehicles, logging, and grazing (Kagan et al. 2006; CNPS 2009). Occurrences in protected areas are threatened by off-road vehicle use (Barbara Ullian, pers. comm., 2000). Epilobium oreganum, can tolerate some cover, and therefore may be less affected by encroaching vegetation than some other rare low growing forbs of Darlingtonia wetlands (Kagan et al. 2006).

Ecology & Habitat

Habitat

This species grows in open, wet, boggy, serpentine sites, also occurring on wet, gently sloping stream banks and meadows, at mostly at 335-800 m elevation, but the full elevation range reported is 200 - 1800 m (FNA 2021, Jepson Flora Project 2025). Associated plants include California pitcher-plant (Darlingtonia californica), sedges, and other bog species.

Terrestrial Habitats

Grassland/herbaceousBarrens

Palustrine Habitats

HERBACEOUS WETLANDBog/fenRiparian

Other Nations (1)

United StatesN3

Province	Rank	Native
Oregon	S2	Yes
California	S2	Yes

Threat Assessments

Threat	Scope	Severity	Timing
2 - Agriculture & aquaculture	Large - restricted	Moderate or 11-30% pop. decline	High (continuing)
2.3 - Livestock farming & ranching	Large - restricted	Moderate or 11-30% pop. decline	High (continuing)
3 - Energy production & mining	Small (1-10%)	Extreme or 71-100% pop. decline	High (continuing)
3.2 - Mining & quarrying	Small (1-10%)	Extreme or 71-100% pop. decline	High (continuing)
5 - Biological resource use	Restricted (11-30%)	Moderate or 11-30% pop. decline	High (continuing)
5.3 - Logging & wood harvesting	Restricted (11-30%)	Moderate or 11-30% pop. decline	High (continuing)
6 - Human intrusions & disturbance	Restricted (11-30%)	Serious - moderate	High (continuing)
6.1 - Recreational activities	Restricted (11-30%)	Serious - moderate	High (continuing)
7 - Natural system modifications	Large (31-70%)	Moderate or 11-30% pop. decline	High (continuing)
7.1 - Fire & fire suppression	Large (31-70%)	Moderate or 11-30% pop. decline	High (continuing)
7.1.2 - Suppression in fire frequency/intensity	Large (31-70%)	Moderate or 11-30% pop. decline	High (continuing)
7.2 - Dams & water management/use	Restricted (11-30%)	Moderate or 11-30% pop. decline	High (continuing)

Plant Characteristics

DurationPERENNIAL

Economic Value (Genus)No

Roadless Areas (2)

California (2)

Area	Forest	Acres
Lake Eleanor	Shasta-Trinity National Forest	397
Weaver Bally	Shasta-Trinity National Forest	829

References (14)

Abrams, L. 1951. Illustrated flora of the Pacific states: Washington, Oregon, and California. Vol. 3. Geraniaceae to Scrophulariaceae. Stanford Univ. Press, Stanford, California. 866 pp.
California Native Plant Society (CNPS). 2009. Inventory of Rare and Endangered Plants. California Native Plant Society. Sacramento, CA. Online. Available: http://www.cnps.org/inventory (accessed 2009).
Flora of North America Editorial Committee (FNA). 2021. Flora of North America north of Mexico. Vol. 10. Magnoliophyta: Proteaceae to Elaeagnaceae. Oxford Univ. Press, New York. xxiv + 456 pp.
Frost, E., R. Sweeney, W. Bigg. 2004. Distribution and Environmental/Habitat Relations of Five Endemic Plants associated with Serpentine Fens in Southwest Oregon and Northwest California. Prepared for U.S. Forest Service and Medford District Bureau of Land Management. Downloaded from: https://www.academia.edu/33511977/Distribution_and_Environmental_Habitat_Relations_of_Five_Endemic_Plants_Associated_with_Serpentine_Fens_in_Southwest_Oregon_and_Northwest_California
Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
Jepson Flora Project (eds.) 2025. Jepson eFlora. Online. Available: https://ucjeps.berkeley.edu/eflora/ (accessed 2025).
Kagan, J., L. Hoover, J. McRae, W. Rolle, M. Mousseaux, L. Mazzu, S. Friedman. 2006. Conservation Agreement for Hastingsia bracteosa, H. atropurpurea, Gentiana setigera, Epilobium oreganum, and Viola primulifolia ssp. occidentalis and serpentine Darlingtonia wetlands and fens from Southwestern Oregon and Northwestern California. U.S. Fish and Wildlife Service. Online. Available: https://ecos.fws.gov/ecp/report/conservation-plan?plan_id=3981 https://ecos.fws.gov/docs/plan_documents/tcca/tcca_461.pdf (Accessed 2024).
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Meinke, R.J. 1982. Threatened and Endangered Vascular Plants of Oregon: An Illustrated Guide. U.S. Fish and Wildlife Service, Region 1, Portland, Oregon. 326 pp.
NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2025. Version: 2.1.1 (released April 04, 2025).
Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).
Ullian, Barbara. 2000. Conservation Director, Siskiyou Project. Personal communication.

Epilobium oreganum

Habitat

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