Bay Bolete

Appearance

"Imleria badia" fruit bodies have a chestnut to dark brown cap, which is almost spherical in young specimens before broadening and flattening out to a diameter of up to 15 cm. The cap margin is acute, and cap surface velvety when young and slightly sticky when wet or old. The cap cuticle is difficult to separate from the flesh underneath. 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. The pores are initially circular, becoming more angular with age, and number about one or two per millimetre. The tubes are 0.8–1.5 cm long, and are adnate to depressed around the area of attachment to the stipe.

The flesh is mostly whitish or yellowish in some places; underneath the cap cuticle, it is brownish-pink or reddish brown. Initially firm, it begins to soften under the cap in older mushrooms. In some parts of the cap, such as the junction of the cap and the stipe, the flesh stains pale blue when injured or exposed to air, particularly in damp weather. This change is sometimes faint, and not persistent, as it eventually reverts to its original colour. The stipe is 4–9 cm long by 1–2 cm thick, and is similar in colour to the cap but paler, and sometimes with a rose-coloured tinge. Its surface has faint longitudinal ridges, a fine powdering, and fine reticulations at the apex. It often has a whitish region at the base and the top, and white mycelium at the base. Unlike the bulbous stipe of many other boletes, the stipe of "B. badius" remains relatively slim and cylindrical. The flesh of the stipe gets tougher with age. Its smell has been described as fruity.

The spore print is olive to olive-brown. The smooth spores are somewhat oblong to slightly ventricose, and measure 10–14 by 4–5 µm. The basidia are four-spored and measure 25–35 by 8–10 µm. Pleurocystidia are fuse-shaped and ventricose, with dimensions of 50–60 by 10–14 µm.

Variety "B. b. macrostipitatus" differs from the main form by its grey-orange cap, shorter stipe measuring 5–7 cm, longer spores, and longer pleurocystidia. The variety "B. b. glaber" has a smooth stipe, and smaller pleurocystidia and cheilocystidia.

Several chemical tests can be used to help identify the mushroom. A drop of ammonium hydroxide solution turns the cap cuticle a greenish to bluish colour. Application of iron sulphate solution causes the flesh to stain a dull bluish-green, while the pores turn golden brown with a drop of dilute potassium hydroxide.

Naming

The similar colouration may cause confusion with "Boletus 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 is "Austroboletus gracilis", but this species does not have a blue bruising reaction, and its pore surface is initially white before turning pinkish. Compared to "I. badia", "B. subtomentosus" fruit bodies have narrower stipes, paler brown, dry caps, and wider pores that do not stain blue on bruising. This latter species is not as good to eat. In western North America, "I. badia" is replaced by the similar "B. zelleri", which also grows both on the ground and on rotten wood. The European species "Xerocomus bubalinus" can be mistaken for "I. badia", but it has a paler yellow-brown cap flushed with pinkish-red, and is not sticky when wet.

Distribution

Although the bay bolete is predominantly a mycorrhizal species, it does have some saprophytic tendencies and may be able to use this lifestyle in certain circumstances. The ectomycorrhizae formed between "I. badia" and spruce have active hyphal sheaths and a higher potential to store nitrogen, phosphorus, potassium, magnesium, iron, and zinc than other mycorrhizal types, indicating the fungus is well adapted to acidic stands and its mycorrhizae are very efficient in uptake and storage of macronutrients. Mycorrhizae with Monterey pine have also been described.

The bay bolete is common in coniferous and less commonly mixed woodlands in Europe, from the British Isles, where it is abundant throughout from August to November, east to the Black Sea Region in Turkey. In Asia, the species has been recorded from Jordan mainland China, and Taiwan. The North American distribution extends from eastern Canada west to Minnesota and south to North Carolina, where the mushroom fruits from July to November. It also grows in central Mexico. The variety "B. b. macrostipitatus" is found from eastern Canada south to Maine and New York state, while variety "B. b. glaber" is known from the Atlantic Maritime Ecozone of eastern Canada. 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. They can be prolific, especially in highland areas that are humid and shady. It is commonly found under white pine, spruce, and hemlock, and also occurs under deciduous trees, especially beech. It can also occur in grassy or mossy areas at or near forest margins; Italian restaurateur and cook Antonio Carluccio recalled picking them in the grounds of Blenheim Palace. It does not occur on calcareous soils.

"I. badia" fruit bodies are less affected by insects than other boletes. Orbatid mites such as "Carabodes femoralis", "Nothrus silvestris" and "Oribatula tibialis" eat them, as do squirrels. Several microbial pathogens can damage the fruit bodies, and have had an effect on populations in China, including soft rot caused by "Pseudomonas aeruginosa", and black mould caused by "Mucor", "Sepedonium", "Paecilomyces", and "Diasporangium" species.

Habitat

Although the bay bolete is predominantly a mycorrhizal species, it does have some saprophytic tendencies and may be able to use this lifestyle in certain circumstances. The ectomycorrhizae formed between "I. badia" and spruce have active hyphal sheaths and a higher potential to store nitrogen, phosphorus, potassium, magnesium, iron, and zinc than other mycorrhizal types, indicating the fungus is well adapted to acidic stands and its mycorrhizae are very efficient in uptake and storage of macronutrients. Mycorrhizae with Monterey pine have also been described.

The bay bolete is common in coniferous and less commonly mixed woodlands in Europe, from the British Isles, where it is abundant throughout from August to November, east to the Black Sea Region in Turkey. In Asia, the species has been recorded from Jordan mainland China, and Taiwan. The North American distribution extends from eastern Canada west to Minnesota and south to North Carolina, where the mushroom fruits from July to November. It also grows in central Mexico. The variety "B. b. macrostipitatus" is found from eastern Canada south to Maine and New York state, while variety "B. b. glaber" is known from the Atlantic Maritime Ecozone of eastern Canada. 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. They can be prolific, especially in highland areas that are humid and shady. It is commonly found under white pine, spruce, and hemlock, and also occurs under deciduous trees, especially beech. It can also occur in grassy or mossy areas at or near forest margins; Italian restaurateur and cook Antonio Carluccio recalled picking them in the grounds of Blenheim Palace. It does not occur on calcareous soils.

"I. badia" fruit bodies are less affected by insects than other boletes. Orbatid mites such as "Carabodes femoralis", "Nothrus silvestris" and "Oribatula tibialis" eat them, as do squirrels. Several microbial pathogens can damage the fruit bodies, and have had an effect on populations in China, including soft rot caused by "Pseudomonas aeruginosa", and black mould caused by "Mucor", "Sepedonium", "Paecilomyces", and "Diasporangium" species.

Uses

Often considered a poor relation of the cep, the bay bolete is nevertheless highly regarded as a choice edible mushroom by some authors such as Carluccio. In central Mexico, it is collected from Izta-Popo Zoquiapan National Park and sold in neighbouring markets. It may cause an allergic reaction in some people, and the blue discolouration upon bruising can be offputting, although the staining disappears from white flesh when it is cooked. 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. Unlike most boletes, "I. badia" can be eaten raw. Otherwise it can be fried in butter, or used with meat or fish recipes. Mushrooms can also be frozen, dried, or pickled in cider vinegar, wine, or extra virgin olive oil, and later used in sauces or soups.

The fruit bodies can be used to make mushroom dyes. Depending on the mordant used, colours ranging from yellow, orange, gold, and green-brown can be obtained. Without mordant, a yellow colour is produced.