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

Caloboletus marshii D. Arora, C.F. Schwarz & J.L. Frank

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Scientific name
Caloboletus marshii
D. Arora, C.F. Schwarz & J.L. Frank
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Proposed by
Noah Siegel
Comments etc.
Noah Siegel

Assessment Notes

Taxonomic notes

Extensively detailed as Boletus “marshii” in Mushrooms Demystified (Arora 1986), later formally described as Caloboletus marshii (Frank 2014).

Why suggested for a Global Red List Assessment?

Caloboletus marshii is a widespread bolete in western United States. Most populations are known from the range of its preferred ectomycorrhizal partner, Coast Live Oak. Also occasionally with other oak species around the Central Valley and Sierra Nevada foothills in California, and scattered populations in the Willamette Valley of Oregon, and Columbia River valley in southern Washington.

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

Geographic range

Occurring from southern California, USA into Humboldt County in coastal/Coast range forests, typically with Coast Live Oak (Quercus agrifolia); scattered populations inland around the Central Valley, and the Sierra Nevada foothills of California, and more rarely with Quercus garryana in the Willamette Valley of Oregon, and Columbia River valley into Washington.

Population and Trends

Population is widespread, and appears stable; no decline has been noted.

Population Trend: Stable

Habitat and Ecology

Ectomycorrhizal with oaks (Quercus spp.), especially Coast Live Oak (Quercus agrifolia). Typically fruiting in late summer or early fall, even before the seasonal rains.


Urban development leading to loss of habitat. Invasive plants, especially grasses growing in oak woodlands.

Conservation Actions

Control invasive plants in oak woodlands.

Research needed

No specific research is needed with regards to this species.

Use and Trade


Arora, D. 1986. Mushrooms Demystified. Ten Speed Press: Berkeley, CA. 959 p.

Frank, J.L. 2014. Nomenclatural Novelties. IndexFungorum No. 194: 1.

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

Country occurrence

Regional Population and Trends

Country Trend Redlisted