Cinnamon bracket

Appearance

The cap is fan-shaped to semicircular and convex, reaching a diameter of 2.5–12 cm . It lacks a stalk, and is instead attached broadly to the substrate. The fruit bodies are initially soft and spongy, but become hard and brittle once they have lost their moisture. The cap surface is covered with matted hairs, has shallow concentric furrows, and a dull brownish-orange color. The flesh is up to 3 cm thick at the thickest part, and is a pale cinnamon color. The pore surface is yellowish to brownish, and the pores are angular, numbering about 2–4 per millimeter. In young fruit bodies, the pore surface bruises reddish brown. The mushroom's odor and taste ranges from sweetish to indistinct.

Fruit bodies produce a white spore print. Spores are elliptical to cylindrical, smooth, hyaline , and measure 3.5–5 by 2–3 μm. The basidia are club shaped and four-spored, with dimensions of 18–22 by 5–5.6 μm. ''H. nidulans'' has a monomitic hyphal system, containing only generative hyphae with clamp connections. In the flesh, these hyphae are thick-walled and highly branched, measuring up to 10 μm in diameter; hyphae comprising the pores and the subhymenium are thinner and less branched. A chemical test can be used to help identify ''H. nidulans'': all parts of the fruit body will instantly stain bright violet if a drop of an alkaline solution is applied. Dilute potassium hydroxide , is often used for this purpose.

Naming

Some other polypores are roughly similar in appearance to ''H. nidulans'' and might be confused with it. ''Phellinus gilvus'' has a yellowish to rusty-yellow fibrous cap, yellowish-brown flesh that stains black in KOH, and a grayish-brown to dark brown pore surface. ''Hapalopilus croceus'' produces large fruit bodies with caps up to 20.5 cm in diameter. Its pore surface is bright reddish orange when fresh, and its flesh stains red with KOH. ''Pycnoporus cinnabarinus'' has a tougher fruit body and is a brighter red color. The edible "beefsteak fungus" ''Fistulina hepatica'' may readily be confused with ''H. nidulans''. It has soft, blood-red fruit bodies that ooze red juice. Also edible, the "chicken of the woods", ''Laetiporus sulphureus'', has bright yellow fruit bodies whose color fades in age.

Distribution

A saprobic species, ''Hapalopilus nidulans'' causes a white rot in its host. Fruit bodies of the fungus grow singly, in groups, or in fused and overlapping clusters on the wood of dead and decaying deciduous trees. Preferred hosts include ''Quercus'' , ''Fagus'' , and ''Betula'' , although on rare occasions it has been recorded on conifer wood as well. In central Europe, its preferred host is oak, while in northern Europe it is found most commonly on ''Corylus'' and ''Sorbus''. Fruiting typically occurs from early summer to autumn, but the tough fruit bodies are persistent and may be encountered out of the usual growing season.

''Hapalopilus nidulans'' has a mostly circumboreal distribution in the north temperate zone, and has been found in North Africa, Asia, Europe, and North America. Outside of this region, it has been recorded from Australia, and Oceania. In North America, where it can be found as far north as the Northwest Territories in Canada, it is more common in the eastern and southwestern part of the continent. In Europe, its northern distribution extends to Porsanger in Norway. Reported for the first time from India in 2011, it was found in forests depots of Chhattisgarh, growing on the stored logs of several native trees: ''Anogeissus latifolia'', ''Chloroxylon swietenia'', ''Desmodium oojeinense'', ''Shorea robusta'', and ''Terminalia elliptica''.

Fungus beetle species known to inhabit and rear their young in the fruit bodies of ''Hapalopilus nidulans'' include ''Sulcacis affinis'', ''Hallomenus axillaris'', ''H. binotatus'', and ''Orchesia fasciata''.

Habitat

A saprobic species, ''Hapalopilus nidulans'' causes a white rot in its host. Fruit bodies of the fungus grow singly, in groups, or in fused and overlapping clusters on the wood of dead and decaying deciduous trees. Preferred hosts include ''Quercus'' , ''Fagus'' , and ''Betula'' , although on rare occasions it has been recorded on conifer wood as well. In central Europe, its preferred host is oak, while in northern Europe it is found most commonly on ''Corylus'' and ''Sorbus''. Fruiting typically occurs from early summer to autumn, but the tough fruit bodies are persistent and may be encountered out of the usual growing season.

''Hapalopilus nidulans'' has a mostly circumboreal distribution in the north temperate zone, and has been found in North Africa, Asia, Europe, and North America. Outside of this region, it has been recorded from Australia, and Oceania. In North America, where it can be found as far north as the Northwest Territories in Canada, it is more common in the eastern and southwestern part of the continent. In Europe, its northern distribution extends to Porsanger in Norway. Reported for the first time from India in 2011, it was found in forests depots of Chhattisgarh, growing on the stored logs of several native trees: ''Anogeissus latifolia'', ''Chloroxylon swietenia'', ''Desmodium oojeinense'', ''Shorea robusta'', and ''Terminalia elliptica''.

Fungus beetle species known to inhabit and rear their young in the fruit bodies of ''Hapalopilus nidulans'' include ''Sulcacis affinis'', ''Hallomenus axillaris'', ''H. binotatus'', and ''Orchesia fasciata''.

Uses

The fruit bodies of ''H. nidulans'' are neurotoxic if ingested. The toxin was identified as polyporic acid, a terphenyl compound first identified from a mycelial culture of the fungus in 1877. This chemical, present at 20–40% of the dry weight of the fruit bodies, inhibits the enzyme dihydroorotate dehydrogenase. It is found in other mushrooms, but in much lower amounts. In a poisoning case reported in 1992, one German family who consumed ''H. nidulans'' experienced nausea, impaired movement, visual impairment, liver and kidney failure; symptoms began about 12 hours after consuming the mushroom. Additionally, the urine of all three poisoning victims temporarily turned violet. They recovered fully a week later. Similar symptoms and recovery were reported in a 2013 poisoning case, in which the fungus was confused with the edible ''Fistulina hepatica''. The set of symptoms arising from consumption of ''H. nidulans'' has been called the ''neurotoxic delayed syndrome''.

''Hapalopilus nidulans'' is highly appreciated by those who make mushroom dyes. When used in combination with alkaline fixatives, the fruit bodies can produce striking violet colors.