Lurid bolete

Description

The lurid bolete is a massive bolete with an olive-brown or cream-brownish cap 5-20 cm across, with small pores: yellow in young ones, then orange to red. The smell is weak, and the flesh is firm, yellow, reddish at the bottom of the stem; when cut it turns blue very quickly and strongly. The stem is yellow-orange to reddish, with a distinct darker net with elongated meshes.

It grows from June to October in broadleaved, mixed and coniferous forests, most often under beeches, oaks and firs, also in parks under lindens, more often on calcareous ground. It is moderately common in Poland.

Many boletes turn blue, including poisonous ones, and some specimens are difficult to tell from related species, so we do not recommend it to beginners. Raw or undercooked it causes food poisoning. Do not combine it with alcohol.

Identification features

Cap

Diameter 5-20 cm; at first hemispherical, then flat-arched or cushion-shaped. Surface smooth or suede-like, dry, sticky in damp conditions; colour from cream to brownish-olive (in descriptions also yellow-olive to olive-brown, with red, orange, violet or brown parts); darkens with age. Cuticle strongly attached to the flesh; darkens when pressed.

Hymenophore (underside of the cap)

Tubes long (1-2 cm), notched at the stem, olive (pale yellow in young ones); turn blue when cut. Pores small, at first yellow, then orange to red, olive in very old ones; turn intensely blue when damaged. Often a wine-red layer between the tubes and the flesh is visible (Bataille's line), but not always.

Stem

Height 5-15 cm, thickness 1-3 cm; barrel-shaped in young ones, then club-shaped or cylindrical. Colour from yellow to orange-reddish, wine-red at the base. A characteristic feature: a distinct, darker (rusty-red) net with elongated meshes.

Flesh

Firm; in the cap yellow, in the lower part of the stem reddish to wine-red; when cut it turns strongly, dark blue. Taste mild, smell weak or slightly sour. The raw flesh should not be tasted.

Spore print and spores

Spore print olive to brownish-olive. Spores smooth, elliptic to spindle-shaped; dimensions 9-16 × 4.5-7 µm (descriptions give different ranges; quotient Q = 2.2).

Habitat and distribution

Ecology. A mycorrhizal fungus with broadleaved trees: oak, beech, birch, sweet chestnut; in Czechia var. rubriceps under linden. Grows singly or scattered, mainly on calcareous soils (rarely on acid ones); according to some descriptions also with fir. The fruiting bodies are readily infested by insect larvae.

Distribution. According to some descriptions: North and Central America, Europe, Japan, Australia; according to others confirmed molecularly only in Europe (Austria, Cyprus, Denmark, Estonia, France, Italy, Montenegro, Sweden), and non-European reports require verification. Moderately common in Poland. Not legally protected (Dz.U. 2014 item 1408).

Fruiting. From June to October (according to some descriptions to November).

What can it be confused with?

• Neoboletus erythropus / N. luridiformis (dotted stem bolete) — Also turns blue, but the stem has tiny carmine-red dots instead of a net; cap dark brown; grows on sandy soils under conifers.
• Suillellus queletii (deceiving bolete) — Stem entirely without a net, wine-red at the base.
• Rubroboletus satanas (Satan's bolete) — Larger, more massive, cap pale, different net pattern; flesh turns blue less strongly, in old fruiting bodies a smell of rot. Regarded as poisonous.
• Suillellus mendax — Very similar; cap more downy, net weaker and often limited to the upper part of the stem, usually on acid soils; spores longer (13-15 µm), quotient Q = 2.7.
• Imperator torosus — Rare; indicated as a possible cause of past poisonings after alcohol (confusion with the lurid bolete). Detailed differences - no data.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• The species was described in 1774 by Jacob Christian Schäffer in his series on the fungi of the Regensburg area.
• The fruiting bodies are readily infested by fly larvae; as early as 1847 Anna Maria Hussey noticed that an old fruiting body is a "living mass of larvae".
• The old suspicion of coprine (as in the ink cap) was not confirmed: in 1994 Kiwitt and Laatsch did not find it in this species, but found it in the rare Imperator torosus.
• The blueing after damage is caused by oxidation of variegatic and xerocomic acids.