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

Butyriboletus abieticola (Thiers) D. Arora & J.L. Frank

Go to another Suggested Species...

Scientific name
Butyriboletus abieticola
(Thiers) D. Arora & J.L. Frank
Common names
Mountain Butter Bolete
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Proposed by
Noah Siegel
Comments etc.
Noah Siegel

Assessment Notes

Taxonomic notes

Described as Boletus abieticola (Thiers 1975), from a California, USA collection; later transferred to the genus Butyriboletus (Arora & Frank 2014).

Why suggested for a Global Red List Assessment?

Butyriboletus abieticola is a locally common species, often growing with true firs in high elevation forests in the Sierra Nevada of California, north into Washington in the Cascade Range.

Geographic range

Most populations are known from high elevation fir (Abies spp) forests in the Sierra Nevada, Siskiyou and Cascade Range of California, and the Cascade Rang in Oregon and Washington (iNaturalist 2020, Arora & Frank 2014). Also occasionally seen on the Northern Californian and Oregon coast (Siegel & Schwarz 2016).

Population and Trends

Population is fairly widespread; population appears stable, but not enough data is available showing trends of this species.

Population Trend: Uncertain

Habitat and Ecology

Ectomycorrhizal, associated with Abies sp. especially Red Fir (Abies magnifica) in high elevation forests of the Sierra Nevada and Cascade Range, occasional to rare in coastal forest in northern California and Oregon with Grand Fir (Abies grandis). Fruiting in the summer and early fall.

Temperate Forest


Prolonged droughts and decades of fire suppression have drastically altered the high sierra forest, leading to thicker, denser, Abies dominated forest. As a result, hotter, stand replacing fires (rather than patchwork and understory burns) are commonplace, altering appropriate habitat drastically, and making it ill-suited for this species.

Increase in fire frequency/intensityDroughts

Conservation Actions

Fuels reduction in mid to high elevation Abies forests.

Habitat & natural process restorationHarvest management

Research needed

More data on populations and trends of this species.

Population size, distribution & trends

Use and Trade

This species is edible, and is often collected for food.

Food - human


Arora, D. & Frank, J.L. 2014. Clarifying the butter Boletes: a new genus, Butyriboletus, is established to accommodate Boletus sect. Appendiculati, and six new species are described. Mycologia 106(3): 464-480.

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
Wood, M.G. and Stevens, F.A. 2020. MykoWeb; California Fungi. https://www.mykoweb.com/CAF/species/Butyriboletus_abieticola.html

Country occurrence

Regional Population and Trends

Country Trend Redlisted