Boletus luridus

Names

Scientific: Boletus luridus

English: Lurid Bolete

Old scientific names include Leccinum luridum, Boletus rubeolarius, and Leccinum rubeolarium

Description

The late summer and early autumn is usually the best time to look for boletes, particularly in damp summers. These are the short-lived, umbrella shaped fruit bodies that have tubes beneath the cap rather than gills. The tubes form a sponge like structure where the spores are produced and released.

Boletus luridus is a spectacular species once you get beneath the cap. The cap itself is variably coloured but generally a rather dull tawny brown, sometimes with a pinkish edge. Beneath the cap the pores start out yellowish – green but take on lovely orange colours with maturity. The stem (or stipe) is similarly coloured with varying amounts of yellow, orange and rust and often a clearly visible raised network of ginger coloured lines (looking a bit like fish net stockings!). Where touched or bruised the stipe and cap colour an intense dark blue. If you cut the fruit body in half, the flesh (initially yellowish) will also go blue with areas of red (colour change appears to be an oxidisation of the fungal pigments when they are exposed to air and probably does not serve any particular purpose for the fungus, although it does help us to distinguish species as the colour changes are very variable and don’t occur in all boletes). A particular feature of this species is that a thin, wine coloured line appears above the tubes in the flesh of the cap . Cut out a section of cap to see this.

Boletus luridus is an ectomycorrhizal species; the hyphae (the microscopic filamentous cells that ramify throughout the substrate forming a network known as a mycelium) grow around the host tree roots (left) enabling an exchange of nutrients to take place – mineral soils released by the fungus go to the tree and sugars from the plant to the fungus. Mycorrhizal species can also assist with water uptake and can protect the roots from grazing by soil micro fauna. Without them over 90% of plants and trees would not flourish.

This species forms a symbiotic association with trees called a mycorrhiza. .

Fruiting

Summer to early autumn.

Habitat

On calcareous soils with beech, oak, birch and lime and also with eared willow (Salix aurita), mountain avens (Dryas octopetala) and rock rose (Helianthemum nummularium).

It is possible to target base rich areas of woodland and open grasslands if the latter contain rockrose (or other suitable plants). These species do not always fruit every year so several visits over several years will be needed to find out whether the fungus is present.

Distribution

(Checklist of the British and Irish Basidiomycota Legon & Henrici 2005): Scotland (and elsewhere) occasional or infrequently reported. The total number of records for this species on the Fungal Records Database of Britain and Ireland is 743 of which 54 are from Scotland (FRDBI 2011). NBN Atlas Scotland distribution map.