Suede Bolete
Xerocomus subtomentosus
Also called yellow-cracking bolete, boring brown bolete
A medium bolete with a dry, suede-textured olive-brown cap over large, bright golden-yellow angular pores. The stipe is ribbed rather than netted and lacks red streaking.
Overview
The Suede Bolete takes its name from the texture of its cap, which is finely and densely velvety, matt and soft to the touch like brushed leather. Set against that muted olive-brown surface, the pore layer is a startlingly bright chrome- to golden-yellow, with pores wide and angular enough to be seen clearly without a lens.
It is the type species of Xerocomus, historically a large genus that has since been dismantled, with many of its members moved to Xerocomellus, Hemileccinum and Aureoboletus. What remains under Xerocomus is a smaller group of dry-capped, large-pored boletes with softer flesh than true Boletus.
Widespread and common across the northern hemisphere, it fruits over a long season and remains one of the standard reference species for learning to read pore size, cap texture and stipe ornamentation as separate characters.
How to identify it
Cap
The cap is 4-12 cm across, convex then broadly convex to flat. The surface is dry and conspicuously velvety or suede-like, and coloured olive-brown, yellow-brown, tan or greyish-brown. It may crack shallowly in dry weather, but the flesh revealed in the cracks is pale yellowish rather than red, an important distinction.
Pores
The pore surface is bright golden-yellow to chrome-yellow when young, dulling to olive-yellow with age. The pores are notably large, angular and irregular, often described as compound because smaller pores nest within larger ones. Tubes are adnate to slightly decurrent, and bruising produces a weak blue-green stain or sometimes none at all.
Stipe
The stipe is 4-10 cm long and 1-2 cm thick, equal or slightly tapering, and coloured pale yellow to yellow-brown, often browner toward the base. Its surface is smooth or marked with fine longitudinal ribs and fibrils, which on some collections coalesce into a coarse partial ribbing near the apex, but there is no true raised network and no strong red streaking.
Flesh & spore print
The flesh is whitish to pale yellow, firm at first and softening with age, and either unchanging or blueing very faintly when cut. The spore print is olive-brown.
Where and when it grows
This bolete grows on soil in deciduous and mixed woodland, associating with oak, beech, birch and chestnut, and it also occurs under spruce and pine in mixed stands. It favours mossy banks, grassy woodland rides, path edges and open woodland with well-drained acid to neutral soil, fruiting singly or in scattered troops.
The season is long, running from early summer through late autumn with a peak from August to October. It is widespread and common throughout Europe, temperate Asia and North America, and is one of the more frequently encountered boletes in mixed woodland across that range.
Ecological role
Xerocomus subtomentosus is ectomycorrhizal with a wide range of both broadleaved trees and conifers, which accounts for its broad distribution and its presence in woodland of many different compositions. The fungus sheathes fine root tips, extends absorptive hyphae through the litter and upper mineral soil, and exchanges scavenged nitrogen and phosphorus for tree-derived sugars.
Its generalist host range makes it an early and persistent coloniser of young plantations as well as a resident of mature woodland. Like other soft-fleshed boletes it is regularly attacked by the parasitic mould Hypomyces chrysospermus, and its fruitbodies are readily grazed by fungus gnats and slugs, cycling their nutrients back into the forest floor within days.
Similar species
The Red Cracking Bolete (Xerocomellus chrysenteron) is smaller, cracks far more readily, shows pinkish-red flesh in the cap fissures, has a strongly red-streaked stipe, and blues more distinctly in the pores. Hemileccinum impolitum has a paler buff cap, small round pores and a stipe covered in fine yellow granules.
Xerocomus ferrugineus is extremely close but has a browner cap, whiter flesh and pinkish rather than yellow basal mycelium. The Bay Bolete (Imleria badia) is darker chestnut with a smooth, slightly greasy cap and small round pores that bruise strongly blue. Netted-stalked Boletus species are separated instantly by their raised stipe reticulum and firmer flesh.