Suillus caerulescens is a common ectomycorrhizal fungus, associated with Douglas-fir (Pseudotsuga menziesii) in western North America. There is no evidence of decline: it can be locally abundant where suitable habitat exists. Therefore, it is assessed as Least Concern (LC).
Described by Smith & Thiers (1964). Suillus imitatus var. imitatus is a synonym (Nguyen et.al., 2013).
Widespread across western North America, roughly following the coastal and Sierra Nevada distribution of Douglas-fir (Pseudotsuga menziesii var. menziesii) in California, USA, north through Oregon and Washington into southern British Columbia, Canada. It also occurs in the Rocky Mountains in southern British Columbia and Alberta, Canada, south through Idaho and Montana, and scattered through the mountains in Colorado, Utah, New Mexico and Arizona with Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca). Distribution records in the Rocky Mountains are sparse in comparison to Pacific states collections. Non-native populations occur in Douglas-fir plantations in Argentina.
The population size is large, occurring over a widespread area, and is stable. There is no indication of any decline.
Population Trend: Stable
Ectomycorrhizal, associated with Douglas-fir. Very common, especially in young forests.
There are no major threats to this species. It is common, and found with young to mature trees, in both urban and forested habitats.
This species is edible, but rarely collected for food.
Nguyen, N., J.F. Kerekes, E.C. Vellinga and T.D. Bruns. 2013. Synonymy of Suillus imitatus, the imitator of two species within the S. caerulescens/ponderosus complex. Mycotaxon 122: 389-398.
Nguyen, N., E.C. Vellinga, T.D. Bruns & P. Kennedy. 2017. Phylogenetic assessment of global Suillus ITS sequences supports morphologically defined species and reveals synonymous and undescribed taxa. Mycologia 108: 1216–1228.
Smith AH, Thiers HD. 1964. A Contribution Toward a Monograph of North American Species of Suillus (Boletaceae). Ann Arbor, Michigan: Lubrecht & Cramer.