| Imleria badia | |
|---|---|
 | |
| I. badia under beech and oak | |
Scientific classification | |
| Kingdom: | Fungi |
| Division: | Basidiomycota |
| Class: | Agaricomycetes |
| Order: | Boletales |
| Family: | Boletaceae |
| Genus: | Imleria |
| Species: | I. badia |
| Binomial name | |
| Imleria badia (Fr.) Vizzini (2014) | |
| Synonyms[2] | |
| |
| Imleria badia | |
|---|---|
| Mycological characteristics | |
 | Pores onhymenium |
 | Cap is convex |
 | Hymenium is adnate |
 | Stipe is bare |
 | Spore print is olive to olive-brown |
 | Ecology ismycorrhizal |
 | Edibility ischoice |
Imleria badia,commonly known as thebay bolete, is a species ofpored mushroom. First described scientifically byElias Fries in 1818, the bay bolete was reclassified asXerocomus badius in 1931, and it is still listed thus in several sources. Modernmolecular phylogenetic studies showXerocomus to bepolyphyletic (not descended from the samecommon ancestor), and the bay bolete is not particularly closely related to species in that genus.
Both the common and scientific names refer to thebay- orchestnut-colouredcap, which is almost spherical in young specimens before broadening and flattening out to a diameter up to 15 cm (6 in). On the cap underside are small yellowish pores that turn dull blue-grey when bruised. The smooth, cylindricalstipe, measuring 4–9 cm (1+1⁄2–3+1⁄2 in) long by1–2 cm (1⁄2–3⁄4 in) thick, is coloured like the cap, but paler. Somevarieties have been described from eastern North America, differing from the main type in both macroscopic and microscopicmorphology. The species is found in Eurasia and North America, growing inconiferous ormixed woods on the ground or on decaying tree stumps, sometimes in prolific numbers.
Often considered a poor relation of the cep (Boletus edulis),I. badia is nevertheless regarded as a choiceedible mushroom by some authors, such as food expertAntonio Carluccio, and is sold in markets in Europe and central Mexico. Its mushrooms are less often infested by maggots than other boletes. Several European studies have demonstrated that the mushroom canbioaccumulate sometrace metals from the soil, such asmercury,cobalt, andnickel. Additionally, the mushroom contains apigment that concentrates radioactivecaesium; specimens collected in Europe following the 1986Chernobyl disaster contained several times morecaesium-137 than those collected before the incident.
The bay bolete was first named asBoletus castaneus ßbadius (i.e. asubspecies ofBoletus castaneus) byElias Magnus Fries in 1818.[nb 1] Fries later renamed it as avariety ofBoletus castaneus in 1828,[3] before assigning it distinct species status in his 1832 workElenchus Fungorum.[4] The fungus has been transferred to several genera in itstaxonomic history:Rostkovites byPetter Karsten in 1881;[5]Viscipellis andIxocomus byLucien Quélet in 1886 and 1888, respectively;[6][7] andSuillus byOtto Kuntze in 1898.[8] In 1931,Edouard-Jean Gilbert reclassified it in the genusXerocomus,[9] and many sources still list it thus.[10] Review ofXerocomus strongly suggested it waspolyphyletic, and the genus was not accepted by some mycologists. The stickiness of its wet cap distinguishes the species from others classified inXerocomus, and hence it was left inBoletus until Alfredo Vizzini placed it in its own genus in 2014.[11][12] Genetic analysis published in 2013 shows thatImleria badia is related toB. pallidus andB. glabellus; the three species form aclade known informally as thebadius clade within a larger group (informally called anaxoboletus) in the suborderBoletineae. Other clades within the group include theTylopilus,porcini (=Boletussensu stricto) andStrobilomyces clades, as well as two other groups composed of members of various genera includingXerocomus (the taxa designated asXerocomus species in this clade are notXerocomus species and require new taxonomic designations) andXerocomellus.[13]
The speciesBoletus limatulus, originally published byCharles Christopher Frost in 1874,[14] was later redescribed, "with a slight tinge of irritation at the time, energy and gasoline spent", as a variety ofI. badia byWally Snell in 1945 (asXerocomus badius var.limatulus).[15] Thetaxon name comes from theLatinlimatulus, "rather polished" or "refined".[16] Varietiesglaber andmacrostipitatus were described fromNova Scotia, Canada, in 1976.[17]
The starting date of fungal taxonomy had been set as January 1, 1821, to coincide with the date of the works of Swedish naturalist Elias Magnus Fries, the "father of mycology".Rolf Singer argued that setting the starting date earlier toChristiaan Persoon's 1801 publication ofSynopsis would make a name change necessary, as he had originally given what is now known asRoyoporus badius the combinationBoletus badius Pers. and if the bay bolete was classified in the genusBoletus, the name would be unavailable and the namesBoletus glutinosusKrombh. orB. spadiceus Krombh. (non Fr.) would have to be used instead.[18]
Thespecies name is the Latin adjectivebadia, meaning "chestnut brown".[19] Thecommon name is likewise derived from the colour of the cap, likened to the coat of abay horse. Alternate common names of a similar derivation include bay-brown bolete and bay-capped bolete,[20] and it is known asbolet bai in French.[21] It is also known as thefalse cep.[20] Varietyglaber was named for its smooth (Latin:glaber, "without hairs") stipe, andmacrostipitatus for its large (Latin:macro, "large") stipe.[17]
Imleria badia fruit bodies have achestnut to dark browncap, which is almost spherical in young specimens before broadening and flattening out to a diameter of up to 15 cm (6 in). The cap margin is acute, and cap surface velvety when young and slightly sticky when wet or old.[21] Thecap cuticle is difficult to separate from theflesh underneath.[22] On the cap undersurface, the pores are initially cream to pale yellow, but become greenish yellow or olive with age. They stain dull blue to bluish-grey when bruised or cut, and are easily removed from the flesh.[21] The pores are initially circular, becoming more angular with age,[23] and number about one or two per millimetre. The tubes are0.8–1.5 cm (3⁄8–5⁄8 in) long,[24] and areadnate to depressed around the area of attachment to thestipe.[25]
The flesh is mostly whitish or yellowish in some places; underneath the cap cuticle, it is brownish-pink or reddish brown.[26] Initially firm, it begins to soften under the cap in older mushrooms.[20] In some parts of the cap, such as the junction of the cap and the stipe,[22] the flesh stains pale blue when injured or exposed to air, particularly in damp weather.[20] This change is sometimes faint,[21] and not persistent, as it eventually reverts to its original colour.[22] The stipe is4–9 cm (1+1⁄2–3+1⁄2 in) long by1–2 cm (1⁄2–3⁄4 in) thick, and is similar in colour to the cap but paler, and sometimes with a rose-coloured tinge.[24] Its surface has faint longitudinal ridges, a fine powdering,[17] and fine reticulations (a net-like pattern of ridges) at the apex.[25] It often has a whitish region at the base[24] and the top,[22] and whitemycelium at the base.[17] Unlike the bulbous stipe of many other boletes, the stipe ofB. badius remains relatively slim and cylindrical.[27] The flesh of the stipe gets tougher with age.[20] Its smell has been described as fruity.[21]
Thespore print is olive to olive-brown.[25] The smoothspores are somewhat oblong to slightly ventricose (fattened in the middle), and measure 10–14 by 4–5 μm.[24] Thebasidia (spore-bearing cells) are four-spored and measure 25–35 by 8–10 μm. Pleurocystidia (cystidia found on the faces of the tubes) are fuse-shaped andventricose, with dimensions of 50–60 by 10–14 μm.[23]
VarietyB. b. macrostipitatus differs from the main form by its grey-orange cap, shorter stipe measuring 5–7 cm (2–3 in), longer spores (15–18 by 4–5 μm), and longer pleurocystidia (30–55 by 10–14 μm).[24] The varietyB. b. glaber has a smooth (glabrous) stipe, and smaller pleurocystidia (35–40 by 10–15 μm) andcheilocystidia (25–30 by 9–12 μm).[17]
Severalchemical tests can be used to help identify the mushroom. A drop ofammonium hydroxide solution turns the cap cuticle a greenish to bluish colour. Application ofiron(II) sulphate solution causes the flesh to stain a dull bluish-green, while the pores turn golden brown with a drop of dilutepotassium hydroxide.[24]
The similar colouration may cause confusion withBoletus projectellus, but the latter species is usually more robust, and has a reticulated stipe. Additionally,B. projectellus has the largest spores in the Boletaceae, up to about 30 μm in diameter. Another lookalike isAustroboletus gracilis, but this species does not have a blue bruising reaction, and its pore surface is initially white before turning pinkish.[28] Compared toI. badia,B. subtomentosus fruit bodies have narrower stipes, paler brown, dry caps,[29] and wider pores that do not stain blue on bruising. This latter species is not as good to eat.[20] In western North America,I. badia is replaced by the similarB. zelleri, which also grows both on the ground and on rotten wood.[30] The European speciesXerocomus bubalinus can be mistaken forI. badia, but it has a paler yellow-brown cap flushed with pinkish-red, and is not sticky when wet.[31]
Although the bay bolete is predominantly amycorrhizal species, it does have somesaprophytic tendencies and may be able to use this lifestyle in certain circumstances.[22] Theectomycorrhizae formed betweenI. badia andspruce (Picea abies) have active hyphal sheaths and a higher potential to storenitrogen,phosphorus,potassium,magnesium,iron, andzinc than other mycorrhizal types, indicating the fungus is well adapted to acidic stands and its mycorrhizae are very efficient in uptake and storage ofmacronutrients.[32] Mycorrhizae withMonterey pine (Pinus radiata) have also been described.[33]
The bay bolete is common inconiferous and less commonlymixed woodlands in Europe, from the British Isles, where it is abundant throughout from August to November,[34] east to theBlack Sea Region in Turkey.[35] In Asia, the species has been recorded from Jordan[36] mainland China,[37] and Taiwan.[23] The North American distribution extends from eastern Canada west toMinnesota and south toNorth Carolina, where the mushroom fruits from July to November.[38] It also grows in central Mexico.[39] The varietyB. b. macrostipitatus is found from eastern Canada south toMaine andNew York state,[24] while varietyB. b. glaber is known from theAtlantic Maritime Ecozone of eastern Canada.[40] Fruit bodies appear singly or scattered on the ground, or on decaying tree stumps, and can be well hidden by pine needles and ferns. Fruiting tends to peak three or four days after rain during warm weather.[41] They can be prolific, especially inhighland areas that are humid and shady.[22] It is commonly found underwhite pine, spruce, andhemlock,[26] and also occurs under deciduous trees, especiallybeech.[22] It can also occur in grassy or mossy areas at or near forest margins;[21] Italian restaurateur and cookAntonio Carluccio recalled picking them in the grounds ofBlenheim Palace.[41] It does not occur oncalcareous (chalky) soils.[27]
I. badia fruit bodies are less affected by insects than other boletes.[28]Orbatid mites such asCarabodes femoralis,Nothrus silvestris andOribatula tibialis eat them,[42] as do squirrels.[41] Several microbial pathogens can damage the fruit bodies, and have had an effect on populations in China, including soft rot caused byPseudomonas aeruginosa, and black mould caused byMucor,Sepedonium,Paecilomyces, andDiasporangium species.[37]
Often considered a poor relation of the cep (Boletus edulis), the bay bolete is nevertheless highly regarded as a choiceedible mushroom by some authors such as Carluccio. In central Mexico, it is collected fromIzta-Popo Zoquiapan National Park and sold in neighbouring markets.[39] It may cause an allergic reaction in some people,[43] and the blue discolouration upon bruising can be offputting,[41] although the staining disappears from white flesh when it is cooked.[44] The flavour is milder than its better-known relative. Younger specimens are best for eating, though more mature ones can be suitable for cutting up and drying. The tendency for the pores to absorb water means that wiping rather than washing is recommended before use in the kitchen.[41] Unlike most boletes,I. badia can be eaten raw (though only young mushrooms should be used). Otherwise it can be fried in butter, or used with meat or fish recipes. Mushrooms can also be frozen, dried,[41] orpickled incider vinegar, wine, or extra virgin olive oil,[45] and later used in sauces or soups.[41]
The fruit bodies can be used to makemushroom dyes. Depending on themordant used, colours ranging from yellow, orange, gold, and green-brown can be obtained. Without mordant, a yellow colour is produced.[46]
In laboratory experiments,extracts ofI. badia fruit bodies have been shown to have significantantioxidative propertiesin vitro.[47] Fruit bodies contain the compoundtheanine,[48] anamino acid and aglutamic acid analogue found ingreen tea.[49] Efforts have been made to establish a protocol for producing theanine by growing the fungus mycelium using submergedfermentation.[50] Severalindole compounds have been detected in fruit bodies. Unprocessed mushrooms containtryptophan (0.68 mg per 100 gdry weight),tryptamine (0.47),serotonin (0.52),kynurenine sulphate (1.96), andkynurenic acid (1.57). Due to their temperature sensitivity, cooking significantly changes the contents and composition of indole compounds: cooked mushrooms contained tryptophan (1.74 mg/100 g dw), 5-methyltryptophan (6.55),melatonin (0.71), andindoleacetonitrile (2.07).[51] Fruit body extracts have been shown to slow the growth of certain tumour cell lines incell culture.[49][52]
Polish studies found that although the mushroom bioaccumulatesmercury andcobalt from the soil, occasional consumption of mushrooms should not cause maximum allowable intake doses to be exceeded.[53][54] Similar conclusions about safety were made in a Polish study of the mushroom's ability to accumulateorganochlorine compounds.[55] Different methods of preparation for consumption affect the leaching rate ofcadmium,lead, and mercury.[56] After the 1986Chernobyl disaster, several studies showedI. badia bioaccumulates radioactive caesium,137Cs.[57]137Cs is produced in nuclear power plants following thechain decay of235U to137Te, and has ahalf-life of thirty years. A German study showed that mushrooms collected from 1986 to 1988 had radiocaesium contents that were 8.3 to 13.6 times greater than mushrooms collected before the accident in 1985.[58] This caesium-sequestering effect is caused by a brownpigment, thepolyphenol compoundnorbadione A, which is related to a family of mushroom pigments known aspulvinic acids.[59] Norbadione A has been investigated for its ability to provide a protective effect against the damaging effects ofionizing radiation. Tests with cell cultures and mice show that although it has some protective effect, it istoxic to cells in higher doses.[60] A new series of alkalichelators based on the structure of norbadione A has been reported.[61] The mushroom may have potential as abioremediation agent to clean upcontaminated sites.[62]
Media related toImleria badia at Wikimedia Commons
Data related toImleria badia at Wikispecies
