What You Should Know
Xerocomus subtomentosus is a species of Bolete fungus in the family Boletaceae. This medium to large mushroom has a brown cap, chrome-yellow pores, and a yellowish stem. 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, although not highly regarded. Its mild taste makes it suitable for mixed mushroom dishes. Elemental analysis of specimens collected from Notec Forest in western Poland determined the mushrooms to have abundant amounts of potassium, phosphorus, and magnesium, with mean values of 46000, 8400, and 1100 milligram/kilogram dry weight, respectively, in the caps. The levels of the toxic metals cadmium, mercury, and lead in the mushrooms "did not pose a threat to a consumer's health".
Other names: Suede Bolete, Brown And Yellow Bolet, Boring Brown Bolete, Yellow-Cracked Bolete, Fluweelboleet (Netherlands), Hřib Plstnatý (Czech Republic), Ziegenlippe (German).
Xerocomus subtomentosus Mushroom Identification
3–12 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.
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.
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 and 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 Cultivation
The place to grow
Forest mushrooms grow in forests and groves, so we have to adapt the choice of location to provide them with conditions as similar as possible to their natural environment - forest trees (oak, pine, birch) should be found there. A shady and quiet place is ideal.
Buy or prepare the mycelium with 5 liters of peat (moistened peat is ideal), 1 liter of charcoal (Instead of charcoal, you can use ashes from a fireplace or fireplace where only wood was used). To improve the parameters, it is also advisable to use 0.5 l of gypsum and 0.5 l of vermiculite or perlite. Moisten the prepared substrate. The ideal way to check if the substrate is properly moistened is to scoop it up with your hands and press it. A few drops of water should come out.
Dig several smaller holes around the tree (preferably so that the roots can be seen), pour in about 0.5 l of the prepared substrate and cover with a 5-centimeter layer of soil. In the places where we poured the substrate, it is advisable to use bark, pine needles, or leaf mulch. Thus, the prepared place does not require any further adjustments, just occasionally sprinkle with a small amount of water. Especially in the period when it rained for 10 to 14 days. Planting can be done from April to late autumn.
Mycorrhiza is a symbiosis of plants with fungi. The fungus draws nutrients from the plants, and the plant gets more coverage thanks to the fungus to obtain water and mineral salts. In addition to physiological and nutritional functions, mycorrhiza protects forest trees from diseases, "nourishes and protects". Mycorrhiza is a very complex process, which is the reason why we do not always manage to achieve success in cultivation. It depends on many factors: mushroom variety, old wood, type of soil, environment, etc. If we prepare the appropriate conditions for development and symbiosis, the first fruiting bodies should appear 2-3 years after inoculation.
Xerocomus subtomentosus Taxonomy and 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.
Xerocomus subtomentosus Synonyms and Varieties
Boletus subtomentosus L., 1753 (basionym)
Boletus crassipes Schaeff., 1774
Boletus cupreus Schaeff., 1774
Boletus kuthanii Assyov & Denchev 2004
Boletus lanatus Rostk., 1844
Boletus leguei Boud., 1894
Boletus pannosus Rostk., 1844
Boletus striipes Fr., 1874
Boletus subtomentosus f. gracilis Killerm. (1925)
Boletus subtomentosus f. leguei (Boud.) Vassilkov (1970)
Boletus subtomentosus f. roseipes Killerm. (1925)
Boletus subtomentosus L. (1753) f. subtomentosus
Boletus subtomentosus L. (1753) subsp. subtomentosus
Boletus subtomentosus L. (1753) var. subtomentosus
Boletus subtomentosus L. 1753
Boletus subtomentosus subsp. punctatipes C. Martín (1904)
Boletus subtomentosus var. albo-ochraceus Pilát (1951)
Boletus subtomentosus var. bulbosus C. Mart. (1894)
Boletus subtomentosus var. conoides Pers. (1800)
Boletus subtomentosus var. crassipes (Schaeff.) Smotl. (1912)
Boletus subtomentosus var. cupreus (Schaeff.) Pers. (1800)
Boletus subtomentosus var. gilvus Alb. & Schwein. (1805)
Boletus subtomentosus var. lanatus (Rostk.) Smotl. (1912)
Boletus subtomentosus var. lepidopodes Opat. (1836)
Boletus subtomentosus var. luteolus Velen. (1922)
Boletus subtomentosus var. marginalis Boud. (1907)
Boletus subtomentosus var. murinus Pers. (1800)
Boletus subtomentosus var. nigricans E.A. Herrm. (1922)
Boletus subtomentosus var. pannosus (Rostk.) Smotl. (1912)
Boletus subtomentosus var. perplexus A.H. Sm. & Thiers (1971)
Boletus subtomentosus var. rubiginosus Pers. (1800)
Boletus subtomentosus var. sanguineus Opat. (1836)
Boletus subtomentosus var. sistotremoides J. Kickx f. (1867)
Boletus subtomentosus var. subbadius R. Schulz (1924)
Boletus subtomentosus var. subbulbosus Pers. (1800)
Boletus subtomentosus var. tesselatus Opat. (1836)
Boletus subtomentosus var. tomentosus Opat. (1836)
Boletus subtomentosus var. virescens Bres.
Boletus xanthus (E.-J. Gilbert) Merlo 1980
Ceriomyces subtomentosus (L.) Murrill, 1909
Leccinum subtomentosum (L.) Gray, 1821
Rostkovites subtomentosus (L.) P. Karst., 1881
Suillus lanatus (Rostk.) Kuntze (1898)
Suillus leguei (Boud.) Kuntze (1898)
Suillus pannosus (Rostk.) Kuntze (1898)
Suillus striipes (Fr.) Kuntze (1898)
Suillus subtomentosus (L.) Kuntze, 1898
Versipellis subtomentosus (L.) Quél., 1886
Xerocomopsis subtomentosus (L.) Reichert, 1940
Xerocomus ferrugineus var. leguei (Boud.) Bon (1994)
Xerocomus flavus Singer & Kuthan, 1976
Xerocomus lanatus (Rostk.) Singer 1946
Xerocomus leguei (Boud.) Montegut ex Bon (1985)
Xerocomus subtomentosus (L.) Quél. (1888)
Xerocomus subtomentosus (L.) Quél. (1888) f. subtomentosus
Xerocomus subtomentosus (L.) Quél. (1888) subsp. subtomentosus
Xerocomus subtomentosus (L.) Quél. (1888) var. subtomentosus
Xerocomus subtomentosus f. rubrotinctus Simonini & Contu (2000)
Xerocomus subtomentosus f. squarrosus A.N. Petrov (1983)
Xerocomus subtomentosus f. xanthus E.-J. Gilbert, 1931
Xerocomus subtomentosus subsp. punctatipes (C. Martín) Dennis (1955)
Xerocomus subtomentosus var. albo-ochraceus (Pilát) Pilát (1974)
Xerocomus subtomentosus var. leguei (Boud.) Maire (1933)
Xerocomus subtomentosus var. luteolus (Velen.) Šutara (2008)
Xerocomus xanthus (E.-J. Gilbert) Curreli (1989)
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