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

Boletus fibrillosus Thiers

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

Assessment Notes

Taxonomic notes

Described by Thiers (1975), based on a Type collection made in Mendocino County, California, USA.

Why suggested for a Global Red List Assessment?

Boletus fibrillosus is a common bolete in northern California and the Pacific Northwest (in both coastal and montane forests), and occasional in the Sierra Nevada on California, and the northern Rocky Mountains.

This species is edible, and is often collected for food; no sign of decline has been noted due to picking.

Population is widespread, and no decline has been observed. We recommend it should be listed as Least Concern (LC).

Geographic range

From southern British Columbia, Canada, throughout the forested parts of the Pacific Northwest, east into the northern Rocky Mountains; south to San Francisco, California, USA in coastal forests, and into the southern Sierra Nevada in the mountains.

Population and Trends

This species is common in conifer forests across much of its range; population is widespread, and shows no sign of decline.

Population Trend: Stable

Habitat and Ecology

Ectomycorrhizal with conifers, in a wide variety of forests types. Fruiting in fall.


No threats have been identified.

Conservation Actions

None needed.

Research needed

Use and Trade

This species is edible, and if often collected for food; although to a lesser extent than other true Boletus species (the Porcini).

Food - human


Desjardin, D.E., Wood, M.G. and Stevens, F.A. 2015. California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.

iNaturalist. Accessed 31 Dec. 2020. https://www.inaturalist.org/observations?place_id=any&taxon_id=118150

Siegel, N. and Schwarz, C. 2016. Mushrooms of the Redwood Coast. Ten Speed Press: Berkeley, CA. 601 p.

Thiers, H. D. 1975. California Mushrooms—A Field Guide to the Boletes. Hafner Press: New York, NY. 261 p.

Country occurrence

Regional Population and Trends

Country Trend Redlisted