Melting Mushrooms – The Common Ink Cap

Common Ink Cap

Kingdom – Fungi

Division – Basidiomycota

Class – Agaricomycetes

Order – Agaricales

Family – Psathyrellaceae

Common Ink Cap
Common Ink Cap

Coprinopsis atramentaria, known as the common ink cap mushroom, is a common and widespread European, North American and Asian mushroom.  This mushroom can be both safely edible yet also poisonous, and clumps of them can be found following rainfall during spring and autumn.  Common ink caps grow from buried wood in grassy areas and disturbed habitats, such as urban areas and lawns.

A clump of young common ink cap mushrooms in a disturbed habitat.
A clump of young common ink cap mushrooms in a disturbed habitat.

The cap of C. atramentaria is dry, grey-brown in colour, 3-6cm tall, ovate and quite smooth when young, though can have fine scales and a scruffy centre with faint grooves.

Young common ink cap.
Young common ink cap.

When it is mature, the cap blackens and becomes a conical-convex shape, which is up to 10cm in diameter and has a tattered or curled margin.  Upon opening, the cap splits and flattens out before disintegrating.  The common ink cap can grow 3-7cm in diameter, and the flesh of the mushroom is thin, soft and grey.

Mature common ink cap
Mature common ink cap

The gills of the common ink cap begin life white in colour, but quickly turn black and easily turn to a liquid.

Young common ink cap gills.
Young common ink cap gills.

The dry, bare, grey stem is 7-17cm high and up to 1.5cm in diameter.  It can be smooth or covered in fine hairs, and is fibrous and hollow.  The almond-shaped spores are 8-11 by 5 μm, and dark brown to black in colour.

Features of the common ink cap.
Features of the common ink cap.

C.atramentaria are strong and resilient, they have been known to burst through hard grounds such as asphalt and pavement. This strength arises from the vertically arranged hyphae in their stems.  

Common ink cap.
Common ink cap.

C.atramentaria undergo auto-digestion, which results in the formation of the inky substance from which it gets its common name. The purpose of this process is to enable the spores to be released more efficiently. The gills are very tightly-packed, but unlike other gilled mushrooms (agarics), instead of shooting spores outwards, the gill surface is dissolved.  This allows the spores to land directly below the mushroom, it also allows the water from the deliquescing edges to evaporate so spores can be transported elsewhere by air currents.  This process of liquefying takes a few hours, and occurs due to an enzyme called chitinase, which breaks up chitin.  Chitin is the material found within fungal cell walls which gives them strength and support.  Once the spores hit maturity in the gills, the chitinase is released on the side of the gills closest to the stem, initiating a chain reaction spreading to the rest of the cap.

The common ink cap
The common ink cap

The common ink cap serves as an important habitat for many bacteria and protist species.  The mushroom is very nutritious, and contains vitamin C, iron, copper and a lot of potassium.  They are low calorie, low cholesterol and contain a lot of fibre. Common ink caps can fruit several times a year.

Common ink cap.
Common ink cap.

C.atramentaria can be eaten safely unless it is consumed in conjunction with alcohol, in which case it can cause some damage (hence its other common name; tippler’s bane). Doing so results in a disulfiram syndrome; producing an acute sensitivity to ethanol.  Symptoms arise 5-10 minutes after consuming alcohol and persist until all alcohol has left the system, and include palpitations, limb tingling, face reddening, nausea and vomiting.  These symptoms can subside in 2-3 hours as long as no more alcohol is consumed.  The severity of the symptoms depend upon the amount of alcohol consumed; the more alcohol, the more severe the symptoms.  If a particularly severe interaction occurs, this may result in a cardiac arrhythmia or even a heart attack.  Symptoms can still occur up to three days after ink cap consumption, if alcohol is consumed.  However symptoms are increasingly mild as time passes.  The sufferer can be treated with fluid replacement, reassurance and monitoring for cardiac arrhythmias.

Common ink cap
Common ink cap

The common ink cap contains a class D toxin called coprine, which has an active substance called 1-aminocyclopropanol.  This substance blocks the action of an enzyme (acetaldehyde dehydrogenase) preventing it from breaking down a component of ethanol (acetaldehyde) that is responsible for hangover symptoms.  This results in the negative effects caused by the consumption of alcohol alongside C. atramentaria.

Coprine structural formula
Coprine structural formula

The common ink cap exudes a black liquid which was once used as ink upon boiling with water and cloves, or urine. This liquid results from the gills of the fungus turning black and liquefying.

Common ink cap.
Common ink cap.

C. atramentaria does not have a distinctive taste, and has either a very faint or no odour. The blackened areas have a more bitter taste, so it is advisable to collect younger specimens or remove the black area from old specimens before consumption (remember – no alcohol!).

Common ink cap.
Common ink cap.

 

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