Suillus luteus

A common fungus native all across Eurasia from Ireland to Korea, it has been introduced widely elsewhere, including North and South America, southern Africa, Australia and New Zealand.

Suillus luteus (literally "yellow pig", from its greasy look in rain) is edible, though not as highly regarded as other bolete mushrooms.

[4] The fungus was reclassified as (and became the type species of) the genus Suillus by French naturalist Henri François Anne de Roussel in 1796.

[8] German naturalist August Batsch described Boletus volvatus (the specific epithet derived from the Latin volva, meaning "sheath", "covering" or "womb"[4]) alongside B. luteus in his 1783 work Elenchus Fungorum.

Batsch placed both of these species, along with B. bovinus and the now obsolete names Boletus mutabilis and B. canus, in a grouping of similar boletes he called "subordo Suilli".

Gray, as the description by Linnaeus had been name sanctioned in 1821 by the "father of mycology", Swedish naturalist Elias Magnus Fries.

[22] Tubes comprising the hymenophore on the underside of the cap are 3–7 mm (0.1–0.3 in) deep, with an attachment to the stipe ranging from adnate to somewhat decurrent.

[16] Good field characteristics for Suillus luteus include the slimy brown cap, glandular dots on the upper stipe, and prominent purplish ring.

Suillus granulatus is yellow fleshed and exudes latex droplets when young, but most conspicuously bears neither a partial veil nor a ring.

[25] Other than that, Suillus luteus is unlikely to be confused with other mushrooms, especially if its preferred habitat under pine trees and the whitish partial veil are considered.

In Europe, the related Suillus grevillei is found under larch and has a yellow cap, while immature fruit bodies of Gomphidius glutinosus may look comparable from above but have gills rather than pores underneath.

[22] In North America, Suillus borealis and S. pseudobrevipes also have partial veils, but lack the distinctive ring of S. luteus.

[26] Suillus luteus is found in coastal and mountainous pine forests and exhibits a tolerance of the northern latitudes.

Southern Hemisphere locales where the slippery jack grow with plantation pines include South America, Africa, Australia, and New Zealand.

[22] In Ecuador, Pinus radiata plantations were planted extensively around Cotopaxi National Park, and Suillus luteus boletes appear in abundance year-round.

[36] The fruiting is so bountiful that the harvest of slippery jacks has become the main reason that pine plantations are established or maintained in parts of Ecuador.

[37] In southern Brazil, it has been recorded in plantations of slash pine (P. elliottii) in the municipalities of Pelotas, Nova Petrópolis and Canela in Rio Grande do Sul, and Colombo in Paraná.

[40] In South Africa, Suillus luteus has been occasionally recorded under pines in Bloemfontein, Johannesburg and Royal Natal National Park.

[22] Suillus luteus produces hydroxamic acid-based siderophores, which are compounds that can chelate iron and extract it from the soil in nutrient-poor conditions.

[52][53] Owing to its frequent rate of sexual reproduction and the resulting extensive gene flow within populations, the fungus can rapidly evolve a trait to tolerate otherwise toxic levels of heavy metals in the environment.

[54] The genetic basis of this adaptation—intriguing to researchers investigating the bioremediation potential of metal-adapted plants and their fungal associates[55]—are contained in the genome sequence of S. luteus, published in 2015.

[27] In a Finnish study, researchers found that 70–95% of fruit bodies collected from typical forest habitats were infested with larvae; the most common species were the flies Mycetophila fungorum, Pegomya deprimata, and Pegohylemyia silvatica.

[58] The fungus produces microscopic crystals of oxalic acid at the surface of its hyphae, a feature that is thought to help deter grazing by the springtail species Folsomia candida.

[66] In Burundi, Suillus luteus mushrooms are sold to Europeans as cepes in Bujumbura but not generally eaten by the Barundi.

[67] Based on samples collected from Chile, the boletes contain (as a percentage of dry weight) 20% protein, 57% carbohydrates, 6% fat, and 6% ash.

"[26] S. luteus and other Suillus species may cause allergic reactions in some people[72] or digestive problems that appear to result from consuming the slimy skin.

" Boletus luteus ", illustrated by Christiaan Sepp
Growing under host tree, Finland
Depicted on a 1964 Soviet Union postage stamp
Slippery jack mushrooms collected in Ukraine
Suillus growing in eastern Siberia