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Boletus edulis, (class Basidiomycetes) is a gourmet, meaty, mild-tasting wild mushroom known by many common names including porcini, penny bun, porcino and cep. It is traditionally described as widely distributed in the holarctic across Europe, Asia, and North America, however recent molecular phylogenetic analyses show that Boletus edulis is taxonomically complex, and requires molecular (DNA) characters to distinguish the distinct species that are easily confused and included in this species (Dentinger and Suz 2014). Multiple studies show the North American, European and Asian mushrooms appear to be very morphologically similar but genetically diverse species. The highly diverse clade of porcini mushrooms (Boletus section Boletus) currently numbers about 36 species and is growing as new species are genetically identified (Feng et al. 2012; Dentinger et al. 2010). While the porcini mushrooms are not indigenous to the Southern Hemisphere, they have been accidentally introduced to Australia New Zealand and Africa (Catcheside and Catcheside 2011; Wang et al. 1995; Hall et al. 1998; SA Forestry Magazine 2009). There is significant export of these mushrooms from their main production areas to markets worldwide, often dried or frozen.
Boletus edulis grows in deciduous and coniferous forests and tree plantations, forming obligate, symbiotic ectomycorrhizal associations with living trees by enveloping the tree's underground roots with sheaths of fungal tissue, assisting the tree in nutrient uptake and benefiting from sugars produced in the tree’s photosynthesis. This relationship makes B. edulis difficult to cultivate, most attempts have been unsuccessful (Regents of the University of California 2014). The fungus produces spore-bearing fruit bodies above ground in summer and autumn. The fruit body has a large brown cap and the stem (stipe) is broad and reticulated stem; the flesh is white (yellowing with age) and non-bruising. Rather than gills, B. edulis (like other boletes) has tubes extending downward from the underside of the cap from which the spores escape at maturity. Boletus edulis have been reported as reaching sizes of 35 cm (14 in) in diameter, up to 25 cm (10 in) tall and 3 kg (6.6 lb) in weight (Kuo 2002; First-Nature)