Inocybe whitei (=Inocybe pudica) — Blushing Fibrecap, blushing fibrehead

Card image cap

Blushing fibrecap3, photograph by Adolf Ceska.

Young blushing fibrecaps12 lacking any obvious pink blush.

Blushing fibrecap13, slight pinking bruising at margin of half cap fragment.

Poisonous

Gills: Adnexed to adnate2, white then grey-brown
Spore print: Yellow brown


Odour: Strong, like sperm.
Cap: (1) 2–4 (8) cm in diameter, bell-shaped to conical when young, expanding to become convex or flattened. The colour is white or slightly yellowish, often with a pinkish blush with age or where bruised. The cap surface is moist when wet with very fine silky, radiating threads that are more evident as the cap dries.
Gills: Closely spaced, adnate or narrowly attached to the stem. Initially white, turning grey-brown as spores mature. Gill edges (seen with a hand lens) remain white.
Stems: 4–10 cm long x 0.4–1.0 cm wide, cylindrical, often slightly thickened at the base. Whitish or slightly grey or brown, often staining pink with age or where bruised.
Ring: Fine threads connecting the margin of the young cap to the stem and vanishing early.
Cup: None.
Spores: 8–10 x 4–6 µm, smooth walled, brown.
Cystidia: Bottle-shaped cells located on the edges and on the sides of gills in this species; 40–65 x 12–22 µm, thick walled, with a cap of crystals.
Habitat: On the ground or under duff, most commonly with Douglas fir (Pseudotsuga menziesii) and with Garry oak (Quercus garryana)1, ectomycorrhizal.
Geographical distribution: North America, Europe.

Many species of fibrecaps have distinctly conical, fibrous caps in colours ranging from grey to brown. The blushing fibrecap is one of a few white species. DNA sequence analysis suggests that not all blushing fibrecaps bruise pink and those that are young or that do not change colour are misidentified as Inocybe geophylla or similar western North American species.
Most Inocybe species are poisonous6. Due to the fibrecap’s small size and unpleasant odour, dogs have been more likely than humans to eat them. Cases of dogs poisoned by Inocybe species are reported almost every year. Fibrecaps have usually been identified only to genus in the poisoning cases. Beug et al.7 found reports of three dogs that died after eating white Inocybe species in Oregon.

Toxins8: Muscarine acts by mimicking the neurotransmitter acetylcholine and incorrectly transmitting nerve impulses to smooth muscles.

Symptoms9: Time of onset usually between 15 minutes and 2 hours, occasionally 5 hours or longer, usually ending in 24 hours. 'SLUDGE' symptoms result, Salivation, Lacrimation (excess tear formation); Urination; Diarrhoea; Gastrointestinal upset; Emesis (vomiting)10.

Treatment11: Contact your regional Poison Control Centre if you or someone you know is ill after eating fibrecaps. 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.

1
MyCoPortal. Mycology Collections Portal, accessed March 2018.
2
Ammirati, J. F., Traquair, J. A. & Horgen, P. A. Poisonous Mushrooms of Canada. Fitzhenry & Whitside Limited, Markham, Ontario (1985).
3
Inocybe whitei UBC F19365; MO75079.
4
Arora, D. Mushrooms Demystified. Ten Speed Press, Berkeley, California (1986).
5
Jacobsson, S. Inocybe (Fr.) Fr. Pp. 868-906 in Funga Nordica, Agaricoid, Boletoid and Cyphelloid Genera (eds Knudsen, H. & Vesteroholt, J.) Nordsvamp, Copenhagen (2008).
6
Kosentka, P. et al. Evolution of the toxins muscarine and psilocybin in a family of mushroom-forming fungi. Plos One 8, 9, doi:10.1371/journal.pone.0064646 (2013).
7
Beug, M. W., Shaw, M. & Cochran, K. W. Thirty-plus years of mushroom poisoning: Summary of the approximately 2,000 reports in the NAMA case registry. McIlvainea 16, 47-68 (2006).
8
Berger, K. J. & Guss, D. A. Mycotoxins revisited: Part II. J. Emerg. Med. 28, 175-183, doi:10.1016/j.jemermed.2004.08.019 (2005).
9
Lurie, Y. et al. Mushroom poisoning from species of genus Inocybe (fiber head mushroom): a case series with exact species identification. Clin. Toxicol. 47, 562-565, doi:10.1080/15563650903008448 (2009).
10
USA Centers for Disease Control. Cholinesterase inhibitors: including insecticides and chemical warfare nerve agents. Part 4: The cholinergic toxidrome. Section 3: Muscarinic acetylcholine receptors. Agency for Toxic Substances and Disease Registry, Atlanta, Georgia <https://www.atsdr.cdc.gov/csem/csem.asp?csem=11&po=9> (2007) accessed June 16, 2017
11
Leikin, J. B. & Paloucek, F. P. Poisoning and Toxicology Handbook, 4th ed., CRC Press, Boca Raton, Florida (2008).
12
Specimen Inocybe whitei UBC F14307, GenBank #AY228341.
13
Specimen Inocybe whitei UBC F32020, GenBank #KX236110.