Boletus edulis - the 'White' Mushroom
Commonly known as penny bun, porcino or cep, and
Beliy Grib meaning 'White' mushroom in the Russian community,
is a basidiomycete fungus, and the type species
of the genus Boletus. Widely distributed in the Northern Hemisphere across Europe, Asia, and North America,
it does not occur naturally in the Southern Hemisphere, although it has been introduced to southern Africa,
Australia and New Zealand. Several closely related European mushrooms formerly thought to be varieties or
forms of B. edulis have been shown using molecular phylogenetic analysis to be distinct species, and others
previously classed as separate species are conspecific with this species. The western North American species
commonly known as the California king bolete (Boletus edulis var. grandedulis) is a large, darker-coloured
variant that was first formally identified in 2007.
The fungus grows in deciduous and coniferous forests and tree plantations, forming symbiotic ectomycorrhizal
associations with living trees by enveloping the tree's underground roots with sheaths of fungal tissue.
The fungus produces spore-bearing fruit bodies above ground in summer and autumn. The fruit body has a large
brown cap which on occasion can reach 35 cm (14 in) in diameter and 3 kg (6.6 lb) in weight.
Like other boletes, it has tubes extending downward from the underside of the cap, rather than gills;
spores escape at maturity through the tube openings, or pores. The pore surface of the B. edulis fruit
body is whitish when young, but ages to a greenish-yellow. The stout stipe, or stem, is white or yellowish
in colour, up to 25 cm (10 in) tall and 10 cm (3.9 in) thick, and partially covered with a raised network
pattern, or reticulations.
Prized as an ingredient in various foods, B. edulis is an edible mushroom held in high regard in many
cuisines, and is commonly prepared and eaten in soups, pasta, or risotto. The mushroom is low in fat and
digestible carbohydrates, and high in protein, vitamins, minerals and dietary fibre. Although it is sold
commercially, it has not been successfully grown in cultivation. Available fresh in autumn in Central,
Southern and Northern Europe, it is most often dried, packaged and distributed worldwide. Keeping its
flavour after drying, it is then reconstituted and used in cooking. Boletus edulis is one of the few
fungi that are sold pickled. The fungus also produces a variety of organic compounds with a diverse
spectrum of biological activity, including the steroid derivative ergosterol, a sugar binding protein,
antiviral compounds, antioxidants, and phytochelatins, which give the organism resistance to toxic heavy metals.