Pleurocybella porrigens — Angel wings

Angel wings

Angel wings2, photograph by Ludovic Le Renard.

Angel wings

Angel wings13, photograph by Adolf Ceska.

Suspect


Gills: decurrent, white
Spore print: white


Odour: Indistinct
Cap: 1.5–10 cm in diameter, shape vase-like and open on one side, tongue-like, or ear-shaped. May be fan-shaped when growing on the side of a log. Caps gradually narrow towards the base. The cap is white to ivory, thin-fleshed and translucent. The surface is smooth. The flesh is pliable. As caps expand sideways, consistent with their common name, they sometimes look like angel wings.
Gills: Rather crowded, narrow, and covering the entire under surface of the mushroom, white.
Stem: Virtually absent.
Ring or veil: None.
Cup: None.
Spores: 5–7.5 x 4–6 µm, smooth.
Habitat: Often in troops and clusters, on coniferous wood, often on western hemlock (Tsuga heterophylla), on fallen tree trunks and on stumps in coastal coniferous forests. Saprotrophic.
Geographical range: Widespread in the boreal and northern parts of North America and Eurasia. Reported from Alaska southwards into northern California.

At least two and probably more closely related, similar-looking species are all known as angel wings, P. porrigens. Angel wings resemble oyster mushrooms (Pleurotus spp.), but oyster mushrooms are common on hardwoods, whereas angel wings only grow on conifer wood. Oyster mushrooms are rarely pure white, and they are thicker and fleshier than angel wings. Pleurotus spores are cylindrical, and angel wings' spores are broadly ellipsoid.

Eating angel wings was linked to a 2004 outbreak of serious illness and death in Japan5-9. This was surprising because angel wings had previously been widely eaten and enjoyed as a seasonal delicacy in that country. Much remains unclear about the outbreak including exactly which of the 'angel wings' species was involved and what kind of toxin was responsible. Given the unknowns and possible risks, consumption of Pacific northwest and BC angel wings is not recommended, especially for people with kidney disease.

Toxins: Uncertain, but perhaps a chemical that is normally removed by kidneys. Analyses showed that these mushrooms contain an unusual amino acid10, fatty acid11, and hydrogen cyanide5,12, one or more of which may cause poisoning.
 
Symptoms: Time of onset was from one to 31 days after eating angel wings. Patients experienced difficulty moving or some level of paralysis, muscle spasms, and later, convulsions6.
 
Treatment: Contact your regional Poison Control Centre if you realize you or someone you know has become ill after eating angel wings. Poison centres provide free, expert medical advice 24 hours a day, seven days a week. If possible, save the mushrooms or some of the leftover food containing the mushrooms to help confirm identification.

Poison Control:
British Columbia: 604-682-5050 or 1-800-567-8911.
United States (WA, OR, ID): 1-800-222-1222.

Cases: Evidence that angel wings caused the poisoning was circumstantial. In 2004 in Japan, 59 people showed symptoms of damage to the brain and 19 died5. All those who became ill had eaten a Japanese species under the name Pleurocybella porrigens and no other factor could be linked to the deaths. The average age of victims was ~69 and most had underlying kidney disease6. Over 200 dialysis patients in Japan reported eating angel wings over the same time period without any symptoms of poisoning but some level of person-to-person variation in sensitivity to mushroom poisoning is common.

1
MyCoPortal. Mycology Collections Portal, <http://mycoportal.org/portal/collections/harvestparams.php> accessed March 2018.
2
Specimen Pleurocybella porrigens UBC F33075, GenBank #MF908476.
3
Trudell, S., Ammirati, J. F. & Mello, M. Mushrooms of the Pacific Northwest. Timber Press, Portland, Oregon (2009).
4
Arora, D. Mushrooms Demystified. Ten Speed Press, Berkeley, California (1986).
5
Gonmori, K., Fujita, H., Yokoyama, K., Watanabe, K. & Suzuki, O. Mushroom toxins: a forensic toxicological review. Forensic Toxicology 29, 85-94, doi:10.1007/s11419-011-0115-4 (2011).
6
Gejyo, F. et al. A novel type of encephalopathy associated with mushroom Sugihiratake ingestion in patients with chronic kidney diseases. Kidney International 68, 188-192, doi:10.1111/j.1523-1755.2005.00393.x (2005).
7
Kato, T. et al. An outbreak of encephalopathy after eating autumn mushroom (Sugihiratake; Pleurocybella porrigens) in patients with renal failure: a clinical analysis of ten cases in Yamagata, Japan. No To Shinkei 56, 999-1007 (2004).
8
Saviuc, P. & Danel, V. New syndromes in mushroom poisoning. Toxicol. Rev. 25, 199-209, doi:10.2165/00139709-200625030-00004 (2006).
9
Beug, M. W. Pleurocybella porrigens toxin unmasked?, <http://www.namyco.org/pleurocybella_toxin.php> accessed May 24, 2017.
10
Wakimoto, T. et al. Proof of the existence of an unstable amino acid: Pleurocybellaziridine in Pleurocybella porrigens. Angewandte Chemie-International Edition 50, 1168-1170, doi:10.1002/anie.201004646 (2011).
11
Hasegawa, T., Ishibashi, M., Takata, T., Takano, F. & Ohta, T. Cytotoxic fatty acid from Pleurocybella porrigens. Chem. Pharm. Bull. (Tokyo) 55, 1748-1749, doi:10.1248/cpb.55.1748 (2007).
12
Akiyama, H. et al. Determination of cyanide and thiocyanate in sugihiratake mushroom using HPLC method with fluorometric detection. J. Health Sci. 52, 73-77, doi:10.1248/jhs.52.73 (2006).
13
Pleurocybella porrigens UBC F28032 MO 112884.