Xerocomus subtomentosus: The Ultimate Mushroom Guide
About The Xerocomus subtomentosus Mushroom
Xerocomus subtomentosus (syn. Xerocomus subtomentosus and Ceriomyces subtomentosus) is a species of bolete fungus in the family Boletaceae. This medium to large bolete is commonly known as suede bolete or yellow-cracked bolete. It has a brown cap, chrome-yellow pores, and yellowish stem and grows with a wide range of hardwood and conifer trees. It occurs throughout Eurasia, North America, and Australia and grows with a wide range of hardwood and conifer trees. It forms symbiotic ectomycorrhizal associations with living trees by enveloping the tree's underground roots with sheaths of fungal tissue.
It is edible, though not as highly regarded as other bolete mushrooms.
Other names: Suede Bolete, Brown And Yellow Bolet, Boring Brown Bolete, Yellow-Cracked Bolete.
Xerocomus subtomentosus Identification
Mycorrhizal with a wide variety of hardwoods (including oaks, beech, birches, aspens); growing alone, scattered, or gregariously; summer and fall, or overwinter in warm climates; originally described from Sweden; widely distributed in Europe and North America; also known from Asia and Oceania.
3–9.5 cm; convex, becoming broadly convex; dry; finely velvety; brownish yellow to brown, yellowish-brown, or olive-brown; often becoming cracked in age.
Yellow, becoming olive-yellow with maturity; often bruising blue, or not bruising; pores xerocomoid, 1–3 per mm; tubes to 10 mm deep.
4–7.5 cm long; 1–2 cm thick; equal above a tapered base; dry; solid and tough; sometimes ribbed near the apex or over the upper half, but not reticulate; usually featuring tiny reddish granules on a whitish to the yellowish surface; basal mycelium white.
White; usually turning pale blue in the cap when sliced.
Ammonia dark red on cap; negative on flesh. KOH red to orangish on cap; orangish on flesh. Iron salts negative to gray on cap; negative to gray on flesh.
Olive to olive-brown.
Spores 10–14 x 3.5–5 µm; boletoid-fusiform; smooth; dull yellow in KOH. Hymenial cystidia inconspicuous; 25–40 x 5–10 µm; lageniform or fusiform; smooth; thin-walled; smooth; hyaline. Pileipellis a collapsing trichoderm; golden in KOH; elements 5–12.5 µm wide, smooth; terminal cells cylindric with rounded apices.
Xerocomus subtomentosus Look-Alikes
Has a reddish stem, usually untapered.
The rare European species, described as new to science in 2007, is similar in appearance to X. subtomentosus. It can be distinguished from the latter in the field by the darker reddish-brown tones of the cap and its preference for associating with Populus trees. It has white flesh that becomes yellow-tinged on exposure to air.
Has bright yellow flesh and mycelium.
Found under conifers and also has yellow mycelium.
Xerocomus subtomentosus Taxonomy & Etymology
Xerocomus subtomentosus was first described in 1753 by the father of taxonomy Carl Linnaeus as Boletus subtomentosus. The starting date of fungal taxonomy had been set as January 1, 1821, to coincide with the date of the works of the 'father of mycology', Swedish naturalist Elias Magnus Fries, which meant that the name required sanction by Fries (indicated in the name by a colon) to be considered valid, as Linnaeus' work preceded this date. It was thus written Boletus subtomentosus L.:Fr. However, a 1987 revision of the International Code of Botanical Nomenclature set the starting date at May 1, 1753, the date of publication of Linnaeus' seminal work, the Species Plantarum. Hence the name no longer requires the ratification of Fries' authority.
French mycologist Lucien Quélet had classified a number of Boletus species in the genus Xerocomus, with Xerocomus subtomentosus made the type species. The genus name is derived from the Ancient Greek Xeros "dry" and kome "hair", and refers to the velvety surface of the cap. This classification was disputed, with many authorities not recognising the genus and continuing to use Boletus subtomentosus; however genetic analysis published in 2013 confirmed the distinctness of this species and its close relatives from the core group of fungi in the genus Boletus (sensu stricto).
Its specific name subtomentosus is Latin "finely haired", referring to its cap. Mushroom author David Arora nicknamed the mushroom the boring brown bolete from its lack of taste and appeal.
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