Assessment Notes

Justification

Boletus fibrillosus is a common bolete in northern California and the Pacific Northwest (in both coastal and montane forests), and occasionally recorded in the Sierra Nevada and the northern Rocky Mountains. This species is edible and is often collected for food by foragers, but there is no reported evidence of decline and no significant threats have been identified. It is listed as Least Concern (LC).

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Taxonomic notes

It was described by Thiers (1975), based on a type collection made in Mendocino County, California, USA.

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Geographic range

It occurs 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.

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Population and Trends

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

Population Trend: Stable

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Habitat and Ecology

It is ectomycorrhizal with conifers, in a wide variety of forest types. Fruiting occurs in fall.

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Threats

No specific threats have been identified with regards to this species.

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Conservation Actions

No specific conservation action are needed with regards to this species, and no specific research is needed either.

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Use and Trade

This species is edible, and is often recreationally collected for food, although to a lesser extent than other Boletus species (the Porcini). It does not appear to be subject to much demand in the commercial trade.

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Source and Citation

Siegel, N. 2021. Boletus fibrillosus. The IUCN Red List of Threatened Species 2021: e.T195922930A195928087. Accessed on 22 November 2025.

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• Country occurrence