Suillus Americanus

S. americanus is a bolete found in eastern North American and is mycorrhizal with white pines, especially Pinus strobus.

A) S. americanus growing in grass in a large cluster. B) Collected basidiocarps of ranging size and maturity. C) Spores and basidia, stained with Cotton Blue (400X). D) Stipe detail, showing slight scabrous texture. E) Hymenium detail, showing angular and irregular pore size.
Figure 1. A) S. americanus growing in grass in a large cluster. B) Collected basidiocarps of ranging size and maturity. C) Spores and basidia, stained with Cotton Blue (400X). D) Stipe detail, showing slight scabrous texture. E) Hymenium detail, showing angular and irregular pore size.

Suillus americanus (Peck) Snell, Chicken Fat Mushroom, PLP847_2018_351

S. americanus is a bolete found in eastern North American and is mycorrhizal with white pines, especially Pinus strobus. It was formerly called Boletus americanus Peck (1887), Ixocomus americanus (Peck) E.-J. Gilbert (1931), and Suillus americanus f. americanus (Peck) Snell (1944). This specimen cluster was located about 4 m from a Pinus strobus, in grass. It was collected in East Lansing, MI, just north of the W.J. Beal Botanical Garden.

The specimens are characterized by bright yellow, mucilaginous caps, about 4-5 cm in diameter. They are convex and slightly umbonate. The context is soft, when torn it bruises from yellow to light brown. The hymenium is yellow-brown and composed of pores, which are circular, about 1-2 per mm. Pores are larger near the stipe becoming smaller near the margin. Stipe is pale yellow to brown, slightly scabrous near the cap. Spores are oblong, brown print. S. americanus is considered an edible mushroom (Ostry et al. 2011), but it is known to cause contact dermatitis is certain individuals (Bruhn and Soderberg 1991). Its bright color and gregarious habitat makes it easy to spot when they are fruiting.

References:

  • Bruhn JN, Soderberg MD. Allergic contact dermatitis caused by mushrooms. Mycopathologia. 1991 Sep 1;115(3):191-5.
  • Ostry ME, O’Brien JG, Anderson NA. Field guide to common macrofungi in eastern forests and their ecosystem functions. Government Printing Office; 2011.
  • Wu QX, Mueller GM, Lutzoni FM, Huang YQ, Guo SY. Phylogenetic and biogeographic relationships of eastern Asian and eastern North American disjunct Suillus species (Fungi) as inferred from nuclear ribosomal RNA ITS sequences. Molecular Phylogenetics and Evolution. 2000 Oct 1;17(1):37-47.

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