Suede Bolete

The pale olive or tan cap is initially convex before flattening and measures 4 to 10 cm (1+1⁄2 to 4 in), exceptionally up to 20 cm (7+3⁄4 in) in diameter. It has a velvety tannish surface, occasionally with slits revealing yellow flesh beneath. The skin of the cap is very hard to remove. The pores underneath the cap are yellow and may bruise blue or green before fading somewhat. The stipe lacks a ring and is up to 12 cm (4+3⁄4 in) long and 1–2 cm (1⁄2–3⁄4 in) wide. The spore print is olive-brown. A drop of ammonium hydroxide on the cap instantly produces a mahogany red reaction, which distinguishes it from some other similar species of the genus. The flesh is white and has little taste or smell.

Similar species. The rare European species Xerocomus silwoodensis, 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. X. chrysonemus has bright yellow flesh and mycelium while X. ferrugineus is found only under conifers and also has yellow mycelium. Also similar are X. chrystenteron, X. mendocinensis, X. truncatus, Boletus chrysenteron, B. citriniporus, and B. edulis.

Xerocomus subtomentosus occurs in autumn in forests throughout Eurasia, North America and Australia and forming a mycorrhizal relationship with a wide range of hardwood and conifer trees. It has been recorded from the vicinity of Tangier in Morocco, growing under cork oak (Quercus suber). It is associated with bilberry and other evergreen shrubs of the heath family Ericaceae. Xerocomus subtomentosus is found in subarctic areas of western Greenland, where it is common and grows in association with white birch (Betula pubescens).

Xerocomus subtomentosus is edible, although not highly regarded. Its mild taste makes it suitable for mixed mushroom dishes. An elemental analysis of specimens collected from western Poland determined the mushrooms to have abundant amounts of the electrolytes potassium, phosphorus, and magnesium, with mean values of 46000, 8400, and 1100 milligramme/kilogramme 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".

Its specific name subtomentosus is Latin "finely haired", referring to its cap. Author David Arora nicknamed the mushroom the boring brown bolete from its lack of taste and appeal. Other vernacular names include "yellow-cracked bolete", "suede bolete", and "brown and yellow bolete".