• Proposed
  • 2Under Assessment
  • 3Preliminary Assessed
  • 4Assessed
  • 5Published

Clavariadelphus occidentalis Methven

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Scientific name
Clavariadelphus occidentalis
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Proposed by
Noah Siegel
Comments etc.
Noah Siegel

Assessment Notes

Taxonomic notes

Clavariadelphus occidentalis was described by Methven (1989), from a collection made in Yuba County, California, USA. Prior to this, the western North American species went by the misapplied name Clavariadelphus pistillaris.

Unpublished sequence data suggest multiple species going by the name C. occidentalis.  (See Clements 2018, https://mushroomobserver.org/330896).

Why suggested for a Global Red List Assessment?

Clavariadelphus occidentalis is a common and widespread species in western North America, occurring in both hardwood and conifer forests; from southern California north into Alaska. It has a cylindrical or irregular lengthwise flattened club-like fruit body, with a whitish buff to ochraceous buff color when young, becoming tan to grayish orange in age.

Recent unpublished phylogenetic data has suggested multiple cryptic species in the C. occidentalis group. Until this group gets modern taxonomic work, it should be listed as Data Deficient (DD).

Geographic range

Widespread in western North America, from southeast Alaska, south to southern California, east to the Rocky Mountains.

Population and Trends

Population is widespread and appears stable. However, believed multi cryptic species makes it hard to assess.

Population Trend: Uncertain

Habitat and Ecology

Ectomycorrhizal with hardwoods and conifers, in coastal and montane forests across western North America.


No threats have been identified.

Conservation Actions

Research needed

Clavariadelphus in western North America are in dire need of modern taxonomic work, as preliminary phylogenetic data has suggested multiple cryptic species in the C. occidentalis group.

Use and Trade

None known.


Castellano, M.A., Cázares, E., Fondrick, B. & Dreisbach, T. (2003). Handbook to additional fungal species of special concern in the Northwest Forest Plan. General Technical Report PNW-GTR-572. United States Department of Agriculture, Forest Service, Pacific Northwest Research Station. 144 pp

Methven, A.S. 1989. Notes on Clavariadelphus. III. New and noteworthy species from North America. Mycotaxon 34: 153-179.

Siegel, N. and Schwarz, C. 2016. Mushrooms of the Redwood Coast: A Comprehensive Guide to the Fungi of Coastal Northern California. Ten Speed Press, Emeryville, CA. 602 pp.

Country occurrence

Regional Population and Trends

Country Trend Redlisted