Caloboletus radicans
Description
Caloboletus radicans is a large Bolete that grows low to the ground, often the misshapen caps can be confused with stones or rocks on the ground.
The cap in more mature specimens is often dinted, grooved, or covered in scales, but when you turn the mushroom over you can see the lovely bright yellow pores and bits of red on the stem. When cut in half there is sometimes a red color to the base of the stem and the rest of the flesh slowly turns blue and then shortly after the blue begins to fade.
The pale grey caps are usually dented and misshapen, particularly in more mature specimens. It comes as quite a surprise, therefore, when you look underneath the cap and discover beautiful yellow pores that turn pale to mid-blue if you touch them.
Caloboletus radicans is inedible due to its intense bitterness. A 2012 study on mushroom poisoning in Switzerland by Katharina M. Schenk-Jaeger and colleagues, found Caloboletus radicans to have caused severe gastrointestinal symptoms to those who had consumed it, including recurrent vomiting and bloody diarrhoea.
Common names: Rooting Bolete, Whitish Bolete.
Mushroom Identification
Cap
A pale gray-buff color, the cap reaches between 5 and 20cm. It has a misshapen edge and often cracks from the center as it ages
Pores
The pore surface and tubes are pale yellow bruising blue quickly when damaged
Flesh
Very pale yellow, almost white, turning blue quickly when damaged
Stem
The yellow stem can be straight or swollen and between 7 and 14cm tall, and 3 and 5cm wide. There is a fine reticulum (net-like pattern) over the stem surface and sometimes the base is slightly red at the base. Often tapers at the base and with root-like mycelial strands. It has no ring or skirt
Smell
Unpleasant, slightly astringent
Spore Print
Olive brown
Habitat
The Rooting Bolete is mycorrhizal, growing in association with several trees Beech, Oak, Hornbeam, Lime and sometime Rock Rose. It can be found in small groups and individually.
Look-Alikes
Hemileccinum impolitus
Grows in similar habitat and grows to around the same size, it does not turn blue when cut though and has a smell of Iodine in the base of the stem.
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Smaller less robust species, it has a more obvious red stem that extends over much of it. The stem of the Bitter Beech Bolete is not woody at the very base.
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Has a darker cap and orange flesh in the stem base; it blues instantly when cut.
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Has a white cap and orange or red pores when mature; its flesh turns pale blue when cut and then fades back to its original pallid color.
History
Caloboletus radicans was first named and described scientifically in 1801 by Christiaan Hendrik Persoon, who called it Boletus radicans. In 2014 Italian mycologist Alfredo Vizzini transferred this bolete to the new genus Caloboletus based on new DNA findings; its name then became Caloboletus radicans. Among its synonyms are Boletus radicans Pers., Boletus albidus Roques., and Boletus pachypus Fr.
The generic name Caloletus comes from the Greekcalo- is derived from Greek Calo- meaning pretty, and -bolos meaning 'lump of clay'. The specific epithet radicans means 'rooting', and some but not all fruitbodies display a rooting c
haracteristic, with stout mycelial threads attached to the stem base and extending for some distance into the soil.
Like other boletes found in Britain and Ireland, Caloboletus radicans is an ectomycorrhizal fungus, which means that it forms symbiotic relationships with the root systems of trees. In the case of the Rooting Bolete it has been found to associate mainly with oak trees and less often with beeches.
Video
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