Peppery Bolete

Appearance

One of the smaller boletes, ''Chalciporus piperatus '' has an orange-fawn 1.6–9 cm cap that is initially convex before flattening out in age. The cap surface can be furrowed; shiny when dry, it can be a little sticky when wet. The colour of the pore surface ranges from cinnamon to dark reddish brown in maturity.

When bruised, the pore surface stains brown. Individual pores are angular, measuring about 0.5–2 mm wide, while the tubes are 3–10 mm deep. Slender for a bolete, the stipe measures 4–9.5 cm long by 0.6–1.2 cm thick, and is either roughly the same width throughout its length, or slightly thicker near the base.

The colour of the stem is similar to the cap, or lighter, and there is yellow mycelium at the base. The flesh is yellow, sometimes with reddish tones, maturing to purplish brown. It has no odour. The spore print is brown to cinnamon. Variety ''hypochryseus'' is essentially identical to the main form except for its bright yellow tubes and pores. Variety ''amarellus'' has pinker pores and a taste that is bitter rather than peppery.

The spores are smooth, narrowly fusiform , and measure 7–12 by 3–5 µm. The basidia measure 20–28 by 6–8 µm and are hyaline, four-spored, and narrowly club-shaped, with many internal oil droplets. Cystidia are fusiform, sometimes with a rounded tip, and have dimensions of 30–50 by 9–12 µm. Some are more or less hyaline, while others are encrusted with a golden pigment. The cap cuticle is a trichodermium, an arrangement in which the outermost hyphae emerge roughly parallel, like hairs, perpendicular to the cap surface. These hyphae are 10–17 µm wide and have elliptical to cylindrical cells at their ends that are not gelatinous. Clamp connections are absent from the hyphae.

Naming

French mycologist Pierre Bulliard described the species as ''Boletus piperatus'' in 1790. In its taxonomic history, it has been transferred to the genera ''Leccinum'' , ''Viscipellis'' , ''Ixocomus'' , ''Suillus'' , and ''Ceriomyces'' . It was reclassified and given its current binomial name in 1908 by Frédéric Bataille when he made it the type species of the newly circumscribed genus ''Chalciporus''. The species name ''piperatus'' means "peppery" in Latin. It is commonly known as the "peppery bolete".

''Chalciporus piperatus'' is a member of the genus ''Chalciporus'', with which the genus ''Buchwaldoboletus'' form a group of fungi that is an early offshoot in the Boletaceae. Many members of the group appear to be parasitic.

Two varieties have been described. ''Chalciporus piperatus'' var. ''hypochryseus'' was originally described as ''Boletus hypochryseus'' by Czech mycologist Josef Šutara in 1993, and was moved to ''Chalciporus'' a year later by Regis Courtecuisse. Wolfgang Klofac and Irmgard Krisai-Greilhuber reclassified it as a variety of ''C. piperatus'' in 2006, although some sources continue to regard it as a distinct species. Variety ''amarellus'', first published by Quélet as ''Boletus amarellus'' in 1883 and later transferred to ''Chalciporus'' by Bataille in 1908, was described as a variety of ''C. piperatus'' in 1974 by Albert Pilát and Aurel Dermek. Authorities disagree as to whether or not it has independent taxonomic significance.The fruit body of the North American species ''Chalciporus piperatoides'' are similar, but can be distinguished by its flesh and pores staining blue after cutting or bruising. It has a less peppery taste. Another mild-tasting relative, ''C. rubinellus'', has brighter colours than ''C. piperatus'', including completely red tubes. One European species, ''C. rubinus'', has a shape similar to ''C. piperatus'', but has red pores and a stem covered in red dots.

Distribution

Fruit bodies of ''Chalciporus piperatus'' occur singly, scattered, or in groups on the ground. The fungus occurs naturally in or near coniferous or beech and oak woodlands, often on sandy soils. Fruit bodies appear in Europe in late summer and autumn from August to November. The fungus is widespread across North America, fruiting from July to October in the eastern states and from September to January on the Pacific Coast. It is found in Mexico and Central America. In Asia, it has been collected from Pakistan, West Bengal, and Guangdong Province. In South Africa, it is known from the southwestern Cape Province and the eastern Transvaal Province.

Habitat

''Chalciporus piperatus'' grows in conifer plantations associated with the fly agaric and the chanterelle. It has been recorded under introduced loblolly pine plantations in Santa Catarina and Paraná states in southern Brazil, and under introduced trees in the Los Lagos Region of Chile.

It has also spread into native forest in northeastern Tasmania and Victoria, having been found growing with the native myrtle beech . The rare variety ''hypochryseus'' occurs only in Europe, including Austria, the Czech Republic, Greece, Italy, and Spain. Also rare, variety ''amarellus'' is widespread in European coniferous forests, where it usually found near pines, spruce, and sometimes fir.

Predators

Fruit bodies can be parasitised by the mould ''Sepedonium chalcipori'', a highly specialised mycoparasite that is only known to infect this bolete. Infections result in necrotic mushroom tissue and the production of copious yellow conidia.

Uses

This mushroom contains toxins, and is usually considered inedible. It has been used as a condiment in many countries, with the Italian chef Antonio Carluccio recommending it be used only to add its peppery flavour to other mushrooms. Some recommend that it be well-cooked before consumption to minimize the risk of gastric symptoms, but the peppery taste is lost with cooking, and even more so by reducing it to a powdered form.

Fruit bodies can be used for mushroom dyeing; depending on the mordant used, yellow, orange, or greenish-brown dyes can be made.