• Proposed
  • Under Assessment
  • Preliminary Assessed
  • LCAssessed
  • 5Published

Suillus americanus (Peck) Snell

Search for another Species...

Scientific name
Suillus americanus
(Peck) Snell
Common names
Chicken Fat Mushroom
American suillus
American slippery Jack
Maślak syberyjski, maślak amerykański forma syberyjska
Масленок сибирский
Siberi tatik
klouzek sibiřský
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Preliminary Category
Proposed by
Mitko Karadelev
Tatyana Svetasheva, Susana C. Gonçalves, Izabela L. Kalucka, Armin Mešić
Mitko Karadelev, Pierre-Arthur Moreau, Elena Zvyagina
Comments etc.
Beatrice Senn-Irlet, Daniel Dvořák, Irja Saar, Katerina Rusevska, Sergey Volobuev, Michael Krikorev, Anders Dahlberg, Vladimír Kunca, Gregory Mueller, Noah Siegel

Assessment Notes


Suillus americanus is an edible ectomycorrhizal fungus associated with five-needle pines, across the northern hemisphere. It is common and there is no evidence of significant decline. Therefore, it is assessed as being of Least Concern (LC).

Taxonomic notes

The species was previously known under two names, Suillus sibiricus and S. americanus, and subsumed under S. americanus by Klofac (2013). Molecular data from Nguyen et al. (2016) supported this change due to a lack of discernable phylogenetic structure based on ITS sequences in the S. americanus clade.

Why suggested for a Global Red List Assessment?

Geographic range

Suillus americanus is a widespread species in the Northern Hemisphere. It is found in North America, Central and Eastern Europe, and Asia to Russia, China and Japan, Pakistan and India. It does not occur naturally in the Southern Hemisphere, although it might have been introduced with the establishment of five-needle pine plantations (e.g. Pinus strobus in South Africa). The area of occupancy (AOO) of this species is much larger than 2,000 km², and its extent of occurrence (EOO) is much larger than 20,000 km².

Population and Trends

The population size of Suillus americanus is very large, as it is such a widespread species. Its population may be in decline due to loss of hosts across some of its range, but likely stable in other large areas, especially Russia.

Population Trend: Uncertain

Habitat and Ecology

Suillus americanus is an ectomycorrhizal fungus that associates exclusively with five-needle pines, usually called white pines (e.g. Pinus strobus, P. monticola, P. lambertiana, P. longaeva, P. ayacahuite, P.cembra, P. peuce, P. wallichiana) in natural forests, near-natural forests (extensively used), plantations, and isolated trees.

Boreal ForestTemperate Forest


There appear to be no particular threats worldwide.

In North America, four white pine species, hosts of Suillus americanus, are threatened by the compound effects of white pine blister rust (Cronartium ribicola, a non-native fungus introduced to North America in 1906), mountain pine beetle (Dendroctonus ponderosae), and fire (Dudney et al. 2020). The dramatic declines resulted in the white pine (Pinus albicaulis) being classified as Endangered in the IUCN Red List (Mahalovich and Stritch 2011). In Europe, S. americanus is threatened by habitat loss due to the felling of subalpine forests where its host trees occur (e.g. to build infrastructure for winter sports); one of its two only hosts in Europe, the endemic P. peuce, is classified as Near Threatened (Farjon 2017). Past deforestation and conversion of forests in China has likely resulted in population decline.

Tourism & recreation areasSmall-holder plantationsAgro-industry plantationsNamed species

Conservation Actions

Reducing habitat loss is the main needed action. In North America, efforts to maintain populations of host trees are ongoing. In Europe, many sites are within nature reserves, so threats to the species are reduced.

Site/area protectionResource & habitat protection

Research needed

Careful morphological studies coupled with molecular data from genes other than the ITS, including from type specimens, and host association data are needed to ascertain the (subtle) differences between the varieties and formae within Suilus americanus (Nguyen et al. 2016).


Use and Trade

Suillus americanus is edible, but not much used.

Food - human


Country occurrence

Regional Population and Trends

Country Trend Redlisted