Public Description of Clavariadelphus occidentalis Methven

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Name: Clavariadelphus occidentalis Methven
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 Draft For Macrofungi Of The Pacific Northwest By Chaelthomas (Private)

Description status: Unreviewed

Taxonomic Classification:

Domain: Eukarya
Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Gomphales
Family: Clavariadelphaceae

General Description:

“SPOROCARPS 50-250 mm tall, 7-15 mm in diam. basally, enlarged upward to 10-35 mm in diam., simple, subcylindric to capitate-clavate, base terete, smooth, white to yellow-white to orange-white, pale tan, or yellow.
SPORE-BEARING TISSUE smooth, becoming longitudinally rugose to rugulose, cream pale orange to brown, apex subacute, obtuse or broadly rounded, smooth, becoming rugose or rugulose, concolorous with the hymenium; surface staining slowly, irregularly brown, where cut or bruised, staining more conspicuously downward.
CONTEXT initially solid, white to pallid, on exposure staining slowly, irregularly brown.
ODOR not distinct. TASTE not distinct or bitter.
TRAMAL HYPHAE 3-12 µm in diam., more or less parallel to longitudinally interwoven, inflated (-12 µm) or broadly undulate, branched, clamped; walls thin or irregularly thickened to 1 µm, smooth; clamps uninflated or inflated (-15 µm), sometimes ampulliform; contents amorphous, hyaline to pale yellow in KOH.
GLEOPLEROUS HYPHAE 3-8 (-12) µm in diam., arising from generative hyphae at clamp connections, scattered throughout the trama, thin walled, smooth, cyanophilic.
LEPTOCYSTIDIA 45-80 x2.5-5 µm, cylindric to narrowly clavate, at times apically or subapically branched, thin walled, smooth.
BASIDIA 70-125 × 8-12 µm, clavate, inflated apically at maturity, thin walled or irregularly thickened, pale yellow, acyanophilic, (2-) 4 spored.
STERIGMATA 6.5-12 µm long, incurved.
SPORES broadly ellipsoid, broadly ovate or amygdaliform, 10.5-14 × 6-7.5 µm, thin walled, smooth, hyaline to pale yellow, acyanophilic, inamyloid, spore print white to pale yellow.”3 (formatting added)

Diagnostic Description:
species distribution sporocarp KOH other
Clavariadelphus americanus eastern N. America8 negative8 like C. pistillaris, but associates with oak and pine6 8
C. caespitosus western N. America8 negative4 mixed conifer-hardwood forests8
C. ligula Europe, N. America3 negative conifer associate1, differences from C. sachalinensis are microscopic3
C. occidentalis western N. America tip flat to round, widest at mid-section negative bruises brown, conifer and hardwood associate
C. pallido-incarnatus tip flat to round, pinkish; widest at tip negative lacks basidia
C. pistillaris Europe, eastern N. America3 6 negative beech associate6
C. sachlinensis Asia, Europe, northern N. America3 negative conifer associate1 3, differences from C. ligula are microscopic3
C. subfastigiatus western N. America3 like C. pistillaris, but has red tones3 green bitter taste
C. truncatus Asia, Europe, N. America tip wide, flattened1 12 red sweet taste, conifer associate

Also see Gibson4, Methven8, and Trudell12 (under C. truncatus, C. sachalinensis) for more detailed differential diagnoses.

Note: Methven8 says that C. caespitosus and C. pallido-incarnatus are KOH yellow, which may simply be a negative result.

Please also fill in/correct/expand the above chart.


western North America


on soil or duff, under conifer and hardwood3 12

Look Alikes:

Grey, brown, or purple dyes (depending on mordant)2


1 Arora, Mushrooms Demystified (Ten Speed Press 2d ed. 1986) (as Clavaridelphus pistillaris)

2 A.R. Bessette, A.E. Bessette, The Rainbow Beneath My Feet (Syracuse University Press 2001)

3 Castellano, Cazares, Fondrick, Dreisbach, Handbook to additional fungal species of special concern in the Northwest Forest Plan, USDA Forest Service Pacific Northwest Research Station, General Technical Report PNW-GTR-572 (2003)

4 Gibson, Trial field key to CLUB-SHAPED FUNGI in the Pacific Northwest (rev. 2009)

5 Index Fungorum record 135115

6 Kuo, M. (2005, September). Clavariadelphus occidentalis. Retrieved from the MushroomExpert.Com Web site:

7 Lincoff, National Audubon Society Field Guide to Mushrooms (Alfred A. Knopf 1981)

8 Methven, A.S. 1989. Notes on Clavariadelphus III. New and noteworthy species from North America. Mycotaxon. 34(1):153-179

9 Methven, A.S. 1990. The genus Clavariadelphus in North America. Berlin: Cramer. 192 p.

10 MycoBank record 135115

11 Rogers Mushrooms

12 Trudell & Ammirati, Mushrooms of the Pacific Northwest (Timber Press 2009) (under Clavariadelphus truncatus)

13 Wood & Stevens, The Fungi of California (a MykoWeb Page)


Erroneously identified as Clavariadelphus pistillaris in the past.3 For example, see Arora,1 Lincoff7 (stating that C. pistillaris is found on in western North America), Rogers11 (C. pistillaris widespread in N. America).

Description author: Joseph D. Cohen (Request Authorship Credit)

Created: 2014-02-01 10:51:00 CST (-0500) by Joseph D. Cohen (Joe Cohen)
Last modified: 2014-02-01 16:20:28 CST (-0500) by Joseph D. Cohen (Joe Cohen)
Viewed: 165 times, last viewed: 2020-06-12 18:07:34 CDT (-0400)