known as penny bun
, is a basidiomycete
fungus, and the type species
of the genus Boletus
. Widely distributed in the Northern Hemisphere
, and North America
, it does not occur naturally in the Southern Hemisphere, although it has been introduced
to southern Africa
and New Zealand
. Several closely related European mushrooms formerly thought to be varieties
of B. edulis
have been shown using molecular phylogenetic
analysis to be distinct species. The western North American species commonly known as the California king bolete (Boletus edulis
) is a large, darker-coloured variant that was first formally identified in 2008.
The fungus grows in deciduous and coniferous forests and tree plantations, forming symbiotic ectomycorrhizal associations with living trees by enveloping sheaths of fungal tissue around their underground roots. The fungus produces spore-bearing fruit bodies above ground in summer and autumn. The fruit body consists of a large and imposing brown cap which on occasion can reach at least 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 are released 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.
, commonly known as the yellow-staining milkcap
or the yellow-latex milky
, is a poisonous
species of fungus
in the Russulaceae
family. It produces mushrooms
with pinkish-cinnamon caps
up to 12 cm (4.7 in) wide held by pinkish-white stems
up to 7 cm (2.8 in) long. The closely-spaced whitish to pinkish buff gills
develop wine-red spots in age. When it is cut or injured, the mushroom oozes a white latex
that rapidly turns bright sulfur-yellow. The species, common and widely distributed in North America, grows in the ground in association with conifer
trees. There are several other Lactarius
species that bear resemblance to L. vinaceorufescens
, but most can be distinguished by differences in staining
reactions, macroscopic characteristics, or habitat.