''Caloboletus radicans'', also known as the rooting bolete or whitish bolete, is a large

ectomycorrhizal An ectomycorrhiza (from Greek ἐκτός ', "outside", μύκης ', "fungus", and ῥίζα ', "root"; pl. ectomycorrhizas or ectomycorrhizae, abbreviated EcM) is a form of symbiotic relationship that occurs between a fungal symbiont, or mycobi ...

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

found in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

under broad-leaved trees, fruiting during the summer and autumn months. It has a pale buff or greyish-white cap, yellow pores and a stout stipe, and stains intensely blue when handled or cut. Bitter and inedible, it can cause severe vomiting and diarrhoea if eaten. Until 2014 it was placed in genus '' Boletus'', but has since been transferred to the new genus ''

Caloboletus ''Caloboletus'' is a fungal genus in the family Boletaceae. It was circumscribed by Italian mycologist Alfredo Vizzini with ''Caloboletus calopus'' as the type species. The erection of ''Caloboletus'' follows recent molecular studies that outlin ...

'' based on

molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

data.

Taxonomy

The fungus was first described by the pioneering South African-born mycologist Christian Hendrik Persoon in 1801, who placed it in genus '' Boletus''. Its specific epithet is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''radic-'' 'root', referring to its rooting stipe. The name ''Boletus albidus'' is a later synonym. In 2014, the bolete was transferred to the new genus ''

'' by Italian mycologist Alfredo Vizzini, based on

data. It is often known by the common name of ''whitish bolete''.

Description

The cap diameter ranges from across, and is usually dirty white, greyish-white, ivory white or buff, downy at first, but often finely cracking at the centre as the cap expands. The stipe is 5–8 cm (2–3¼ in) tall by 3–4 cm (1¼–1⅔ in) wide, usually swollen or barrel-shaped when young, but soon becoming elongated and more or less fusiform, with a tapering base usually rooting into the substrate. The apex is typically bright lemon yellow, but fading below. There is a light straw-coloured reticulation at the upper part of the stipe, though in rare occasions this may be indistinct. The flesh is pale yellow, somewhat paler whitish to straw-coloured in the cap, instantly turning dark blue when cut. The pores are lemon yellow, small and rounded, bruising blue when touched or injured. The spore print is olivaceous walnut-brown.Bon M. (1987).The Mushrooms and Toadstools of Britain and North Western Europe. Microscopically, it has ellipsoid to fusiform spores measuring 11.5–14 × 4–5.5 μm. The hyphal structure of the cap is a trichodermium of interwoven septate

hyphae A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

, often finely incrusted.

Distribution and habitat

Fruiting during warm spells in the summer and early autumn, ''Caloboletus radicans'' is ecologically versatile. It forms

associations with a wide range of broad-leaved trees, including oaks (''

Quercus An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably '' ...

''), beech ('' Fagus''), hornbeam (''

Carpinus Hornbeams are hardwood trees in the flowering plant genus ''Carpinus'' in the birch family Betulaceae. The 30–40 species occur across much of the temperate regions of the Northern Hemisphere. Origin of names The common English name ''hornbeam' ...

''), chestnut (''

Castanea The chestnuts are the deciduous trees and shrubs in the genus ''Castanea'', in the beech family Fagaceae. They are native to temperate regions of the Northern Hemisphere. The name also refers to the edible nut (fruit), nuts they produce. Th ...

'') and lime (''

Tilia ''Tilia'' is a genus of about 30 species of trees or bushes, native throughout most of the temperateness, temperate Northern Hemisphere. The tree is known as linden for the European species, and basswood for North American species. In Britain a ...

''). It grows on both

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adje ...

(chalk) and acidic soils in southern England (where it is common) and across much of

Edibility

The mushroom 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.

References

{{Taxonbar, from=Q64785775, from2=Q1478484 radicans Inedible fungi Fungi of Europe Fungi described in 1801 Poisonous fungi Taxa named by Christiaan Hendrik Persoon