Reddening fibrecap

Inocybe godeyi is a smallish fibrecap most easily recognised by the way it reddens.

Cap

Young caps are conical to bell-shaped with a persistent central boss (umbo) and a pale whitish to straw-cream silky surface. As they expand the surface breaks into fine radial fibres, sometimes with small upturned scales near the margin. The cap rarely exceeds 5 cm in diameter.

Gills

Gills are greyish-cream at first, becoming clay-brown with age.

Stem

The stem is fibrillose to finely powdery-white.

By itself this description matches dozens of other Inocybe species and makes definitive identification difficult.

The reddening reaction is the key: slowly cut the base of the stem and press the gill surfaces - within a few minutes the white flesh and pale surfaces flush distinctly pink to brick-red.

This colour change is both a diagnostic character and an important safety signal: no edible species worth confusing with this one shares this reddening pattern.

The spores are smooth and elongated (not angular or star-shaped), which separates it from star-spored relatives, but spore examination requires a hand lens or microscope and a good spore print on white paper.

Seek medical attention promptly if muscarine poisoning is suspected.

The specific antidote is atropine (an anticholinergic agent), which reverses the muscarinic effects. It is given intravenously in hospital and titrated to effect. Self-treatment is dangerous and ineffective.

In children, the elderly and cardiac patients the bradycardia and bronchospasm can be rapidly dangerous.

Bring a specimen, photograph or description of the mushroom to hospital to aid diagnosis. Because I. godeyi may be confused with the potentially lethal Inosperma erubescens, do not assume a mild clinical course.

The primary toxin is muscarine (and related muscarine analogues). It binds irreversibly to muscarinic acetylcholine receptors in the parasympathetic nervous system, mimicking excessive cholinergic stimulation.

Unlike amatoxins, muscarine acts rapidly - symptoms within 15-30 minutes of ingestion. It is also:

• Water-soluble
• Heat-stable, surviving normal cooking temperatures without decomposition
• Not metabolised to a less toxic form in the body

Muscarinic (PSL/SLUDGE) syndrome:

• Profuse sweating (diaphoresis)
• Excessive salivation and lacrimation (watery eyes)
• Severe nausea, vomiting and abdominal cramps
• Watery diarrhoea
• Marked bradycardia (slow heart rate)
• Bronchospasm and increased bronchial secretions (which can cause breathing difficulty)
• Miosis (pupil constriction)
• In severe cases, urinary incontinence and bronchorrhoea

In contrast to amatoxin poisoning, symptoms appear within 15-30 minutes - the rapid onset is both an alarm signal and, fortunately, makes the mushroom connection easier to diagnose.

In most adults the syndrome is very uncomfortable but self-limiting; in severe cases or vulnerable individuals it can be life-threatening due to cardiac and respiratory effects.

Inocybe godeyi contains muscarine, a parasympathomimetic alkaloid that activates muscarinic acetylcholine receptors in the autonomic nervous system. Poisoning occurs within 15-30 minutes of ingestion.

Although most muscarine-poisoning cases from Inocybe are not fatal in healthy adults with prompt medical attention, severe poisoning can be life-threatening, particularly in children, the elderly or those with cardiac or respiratory conditions.

The danger is compounded by the fact that I. godeyi can be confused with the closely related Inosperma erubescens, which has far higher muscarine concentrations and has caused documented fatalities.

Treat any reddening fibrecap as potentially as dangerous as I. erubescens until expert identification rules it out.

This is a species of calcareous-soil broad-leaved woodland and amenity plantings.

It partners mycorrhizally with a range of deciduous trees - oak, beech, lime, hornbeam, hazel and poplar among them - and is consequently as at home in urban parks, churchyards, cemetery avenues and roadside tree strips as in semi-natural woodland.

It prefers well-drained, neutral to basic soils and tends to avoid strongly acidic or waterlogged ground.

Its urban occurrence is a safety concern: casual visitors to parks or people collecting 'edible-looking' small mushrooms may encounter it under ornamental trees and mistake it for innocuous species.

Inocybe godeyi fruits from June through to October, peaking in August to early October in central and western Europe.

Like most Inocybe species it needs warm soil - above 12 °C - and a flush of rain to trigger fruiting.

Individual fruitbodies decay quickly in hot or dry conditions and last only a few days, so a troop that appears after autumn rain may be gone within the week.

Most records cluster in late summer and early autumn when soil is still warm but seasonal moisture begins to build.

Inocybe godeyi lives as a mycorrhizal partner of deciduous trees, its unseen mycelium threaded through the soil in a long-term exchange with its host roots.

Fruitbodies emerge singly or in small scattered groups from bare or litter-covered soil beneath host trees, sometimes on woodland paths, at tree bases or on grassy margins.

It does not grow on wood and is not clustered like saprotrophic species. There is no volva or basal cup, and no ring on the stem - both features that help exclude Amanita species.

Requires warm soil and moderate rainfall; flushes 4-10 days after rain events when soil temperature is in the 12-22 °C range. Late summer and early autumn pulses are most productive.

The Inocybe genus as a whole is notoriously difficult and contains many poisonous species. Several specific lookalike risks apply to I. godeyi.

1. 1Most critically, Inosperma erubescens (brick-red fibrecap, formerly Inocybe erubescens) is a closely related, morphologically similar species with very high muscarine content that has caused fatal poisoning. It also reddens but tends to be more uniformly brick-red coloured from the start and has a stronger spermatic odour - distinguishing the two in the field with certainty is not possible for non-specialists.
2. 2The many non-reddening white or pale fibrecap species (Inocybe geophylla, I. rimosa, I. lacera and relatives) could be confused at early growth stages before the reddening develops.
3. 3Novices sometimes confuse pale fibrecaps generally with small edible white mushrooms or with Marasmius oreades (fairy ring champignon, which grows in open grass rings, has tough wiry stems and gills widely spaced without reddening).

The reddening is a useful positive ID clue for I. godeyi itself, but because its deadly relative I. erubescens also shows reddening, the reddening trait should be treated as a warning, not a reassurance that you have the 'less dangerous' species.