Red Cracking Bolete

The Red Cracking Bolete is one of the most familiar small boletes of European and North American woodland, common enough on mossy banks and path edges that it is often the first bolete a beginner learns after the porcini. Its calling card is the cap surface, which dries and splits into a fine mosaic of plates with pinkish-red flesh visible in the cracks.

It was long placed in Boletus and then in Xerocomus, but now sits in Xerocomellus, a genus of smaller boletes with dry, often cracking caps, comparatively soft flesh, and stipes streaked or flushed red rather than netted. The group has been split repeatedly and several closely similar species travel under this name in the field, so specimens vary.

Slender, soft-fleshed and quick to decay, it fruits over a long season and is easily recognised as a group even when the exact species within the complex is uncertain.

Cap

The cap is 3-8 cm across, convex then flattening, with a dry, matt, finely velvety surface. Colour is olive-brown, greyish-brown or dull sepia. With age and dry weather the surface cracks into an areolate mosaic, and the flesh exposed in the fissures is a distinct pinkish to brick-red, the feature that gives the species its name.

Pores

The pore surface is bright lemon to golden-yellow when young, becoming olive-yellow and finally dull olive-brown. Pores are fairly wide and angular, and the tubes are adnate to slightly depressed. Pressure or bruising turns the surface blue-green within seconds.

Stipe

The stipe is 4-8 cm long and 0.5-1.5 cm thick, more or less equal or tapering downward, and yellow at the apex with strong red or carmine streaking and fibrils over the middle and lower parts. It is smooth and never reticulate, and the base often carries whitish to yellowish mycelium.

Flesh & spore print

The flesh is pale yellow, red beneath the cap cuticle, and turns weakly blue where cut, especially above the tubes, before fading. The texture is soft and quickly becomes spongy. The spore print is olive-brown.

The Red Cracking Bolete grows on soil, in moss and on humus-rich banks in deciduous and mixed woodland, especially under oak, beech and birch, and also in parks, hedgerows and wooded gardens. It is fond of shaded path edges, mossy slopes and the sides of woodland ditches, fruiting singly or in scattered groups.

The season is long, from early summer to late autumn, with peaks in late summer and September. It is widespread and common throughout Europe, and species of the same complex occur across North America and temperate Asia.

This bolete is ectomycorrhizal with a broad range of broadleaved trees, chiefly oak and beech, and occasionally with conifers. Its hyphae ensheath fine root tips and form the Hartig net through which mineral nutrients pass to the tree in exchange for photosynthate. Its wide host range and tolerance of disturbed ground explain why it is common in parks and gardens as well as ancient woodland.

Fruitbodies are among the most heavily parasitised of all boletes: the golden mould Hypomyces chrysospermus frequently smothers them in a white then bright yellow and finally reddish-brown crust, deforming the mushroom completely. Soft-fleshed fruitbodies also decay quickly, returning nutrients rapidly to the litter.

The Suede Bolete (Xerocomus subtomentosus) is larger with a more velvety olive-brown cap that cracks less readily and shows pale yellowish rather than red flesh in any cracks, and its stipe lacks strong red streaking. Xerocomellus cisalpinus is extremely close but blues more strongly in the stipe flesh, while Xerocomellus porosporus has a cap that cracks to show pale, not red, flesh and greyer tones overall.

The Bay Bolete (Imleria badia) is bigger and darker chestnut with a smooth, slightly greasy cap that does not crack and pores that bruise strongly blue. Boletus species proper are firmer-fleshed with thicker stipes, and the netted-stalked species are separated at once by their raised stipe reticulum.