Suillus placidus, is a species of fungus in the genus Suillus

Suillus

Suillus is a genus of basidiomycete fungi in the family Suillaceae and order Boletales. Species in the genus are associated with coniferous trees, and are mostly distributed in northern temperate locations, although some species have been introduced to the Southern Hemisphere.-Taxonomy:The genus...

. It is an edible pored mushroom

Boletales

The Boletales are an order of Agaricomycetes, containing over 1300 species with a diverse array of fruiting body types. The boletes are the best known members of this group, and until recently, the Boletales were thought to only contain boletes...

 found in European and North American coniferous forests, growing in association with several species of pine of the subgenus Strobus.

Description

The cap

Pileus (mycology)

The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...

 of Suillus placidus is hemispherical when young, later becoming convex. It is ivory white in colour and very slimy, growing to 10 cm in diameter. The stem

Stipe (mycology)

thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...

 is slender, ringless and ivory white with grey granular dots or blotches near the top. The soft flesh

Trama (mycology)

In mycology trama is a term for the inner, fleshy portion of a mushroom's basidiocarp, or fruit body. It is distinct from the outer layer of tissue, known as the pileipellis or cuticle, and from the spore-bearing tissue layer known as the hymenium....

 is yellowish white with a mild taste. The spore

Spore

In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

s are ochre.

Ecology

Suillus placidus is found in Asia, Europe and North America occurring exclusively alongside species of five-needled pine of the subgenus Strobus. The ectomycorrhizal

Mycorrhiza

A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....

 association is beneficial for both fungus and tree, and is a form of symbiosis

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

.

In Asia, it is known to occur in the Russian Far East

Russian Far East

Russian Far East is a term that refers to the Russian part of the Far East, i.e., extreme east parts of Russia, between Lake Baikal in Eastern Siberia and the Pacific Ocean...

 with Siberian pine

Siberian Pine

The Siberian Pine, Pinus sibirica, in the family Pinaceae is a species of pine tree that occurs in Siberia from 58°E in the Ural Mountains east to 126°E in the Stanovoy Range in southern Sakha Republic, and from Igarka at 68°N in the lower Yenisei valley, south to 45°N in central...

 (Pinus sibirica), Siberian dwarf pine

Siberian Dwarf Pine

Pinus pumila is a native to northeastern Asia, including the islands of Japan. This shrubby pine ranges from 1–3 m in height, exceptionally up to 5 m, but may have individual branches that extend farther along the ground in length...

 (P. pumila) and Korean pine

Korean Pine

The tree species Pinus koraiensis is commonly called Korean Pine. It is native to eastern Asia, Korea, Manchuria, far eastern Russia, and central Japan. In the north of its range, it grows at moderate altitudes, typically to , whereas further south, it is a mountain tree, growing at to altitude...

 (P. koraiensis). It has also been reported in China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

.

It is rarely seen in Europe, where it is known to form ectomycorrhizal associations with Swiss pine

Swiss Pine

The Swiss Pine or Arolla Pine, Pinus cembra, is a species of pine tree that occurs in the Alps and Carpathian Mountains of central Europe, in Poland , Switzerland, France, Italy, Austria, Germany, Slovenia, Slovakia, Ukraine and Romania. It typically grows at to altitude. It often reaches the...

 (Pinus cembra) and introduced eastern white pine

Eastern White Pine

Pinus strobus, commonly known as the eastern white pine, is a large pine native to eastern North America, occurring from Newfoundland west to Minnesota and southeastern Manitoba, and south along the Appalachian Mountains to the northern edge of Georgia.It is occasionally known as simply white pine,...

(P. strobus). In north-eastern North America, its range coincides with that of the native eastern white pine (P. strobus).

The fungus fruits in summer and autumn with fruiting bodies occurring singly or in small groups.