Coprinus comatus – The shaggy ink cap

This mushroom is not a native, but it grows in Australia.  It is often found in parks and on waste ground and once established in a patch of ground, they will come up year after year.  Often, they favour grassed areas where the grass clippings are allowed to rot down in situ.  The one below is on the edge of the local football oval where it comes up each year with the onset of the first rains and continues to fruit through winter.

Coprinus comatus at the start of deliquescence.

These mushrooms, in common with all the members of the genus, self-decompose into a black inky mess.   The one above is beginning to go through that process and the one below is well into it.

Coprinus comatus, showing outward curl of rim during deliquescense

Sometimes, red droplets can be seen emerging from these mushrooms, in the same manner as some species of Agaricus. This seems to be associated with the spores.

Coprinus comatus, showing red droplets emerging from unopened cap

For culinary purposes, the mushrooms are best picked before the decomposition process has set in.  Decomposing specimens need to be kept apart from fresh ones.   They can be kept in iced water in the fridge for about half a day to avoid onset of the decomposition reaction.

The purpose of the decomposition reaction, sometimes called deliquescence, is related to spore production. Like most mushrooms, this species has a need to disperse it’s spores to the wind. This is difficult because of the cylindrical shape. To overcome this, the spores ripen from the bottom upward, as they do so the cap curls outward and dissolves into a dark inky mass. These actions are due to the influence of enzymes, including at least one chitinase that assists in the breakdown of the chitin in the cell walls. The mushroom contains a range of chitinases, as do other fungi, and they serve different purposes. Some for example assist in the extension of the hyphae and cell rearrangement. The chitinase that is primarily responsible for breaking down the cell structure in the cap does not affect the stipe which needs to maintain structural integrity during spore release.

The decomposition process does not produce anything toxic and the mushrooms can be eaten at any stage. The ‘ink’ can even be used to make a vegan version of squid ink pasta. It can also be used as writing ink, though it needs to happen quickly as it will further decompose under the influence of bacteria. Addition of some essential oil like oil of cloves is said to delay the fermentation of the ink. This use is nowhere near as common as the use of ink made from oak galls and iron salts.

For years I tried to incorporate these mushrooms into dishes without much success.  They always turned into a horrible slimy mess.  Then someone explained the trick.  You need to slice them and then toss them in a pan for a while on low heat until they have lost a good proportion of their moisture.  After that, they can be cooked as you would a normal mushroom.  The de-watering step ensures that they remain firm during the cooking process.

It is also possible to dry these mushrooms if you happen to have a dryer, or if the weather is sunny.  Drying must be done to the point of crispness.  Once dried, they can be used to impart a distinctive flavour to dishes.

Many books declare that this mushroom cannot be eaten with alcohol.  Unfortunately, this is a myth that has been propagated throughout the world.  Some of the confusion is due to the fact that the mushrooms that do cause this problem used to be grouped in the same genus, Coprinus.   With the advent of DNA profiling, things have been changed around and there are now only a few species left in the genus Coprinus.   The offending mushrooms are now in the genus Coprinopsis.  The most well known member of the genus that causes problems with alcohol is Coprinopsis atramentaria, the common ink cap.   Others in the genus contain the same chemical, with Coprinopsis picacea, the magpie fungus of Europe containing more than the common ink cap, though it is seldom consumed because it has an unpleasant smell. It is notable that Coprinopsis and Coprinus are not only different genera, but they are in different families.   Coprinus is in Agaricaceae and Coprinopsis is in Psathyrellacea.  They are not even closely related!

The compound that causes the issues with alcohol is known as Coprine.   It is an unusual amino acid.  There are other unusual amino acids in other fungi that are also responsible for toxic effects.    These are sometimes called non-protein amino acids as they do not belong to the set of amino acids that are incorporated in proteins. Since they are not tied up in proteins they are free to be extracted from the raw mushroom and in this way they enter the digestive system. The structure and breakdown reaction of coprine are shown below.

coprine mechanism

When we consume alcohol, our body processes it in a specific way.   It is first converted to acetaldehyde and then that is acted on by an enzyme called aldehyde dehydrogenase which converts the acetaldehyde to acetic acid.   The aminocyclopropanol in the reaction above blocks the action of aldehyde dehydrogenase and the result is an accumulation of acetaldehyde in the body.   This is toxic and it gives a reaction similar to Antabuse, a drug that has been used to treat alcoholism.
There is no truth in the idea that coprine itself has been used to treat alcoholism.  It has far to many other toxic side effects to be used clinically.   One of those side effects is to cause tumours in the reproductive system of male rats ( or was it mice?).

Somewhat perversely, some of the compounds produced by Coprinus comatus have been shown to reverse liver damage caused by alcohol, at least in a rodent model.

Coprinus comatus is a relatively large mushroom.  It can attain a height of 200 mm or more and is typically 20 to 30 mm in diameter.   It should not be confused with some of the similar looking small species that are sometimes seen on composts for example.  One mushroom of similar stature that occurs in my part of the world is Coprinopsis aff. stangliana.   It is shown in the image below.

Coprinopsis aff. stangliana

Coprinopsis aff. stangliana is so named because it resembles a northern hemisphere species. DNA studies suggest however that it is a native, at least in Western Australia where it can be found from Perth southward to at least Margaret River. It is common in the Tuart Forest. It rivals Coprinus comatus in size, sometimes reaching 300mm in height. A large specimen is shown in the image below.

Coprinopsis aff. stangliana showing long stipe, outward curled cap and deliquesence.

The spores of Coprinopsis aff. stangliana are shown below.

Spores of Coprinopsis aff. stangliana

Another type of ink cap that has some similarity in appearance, though it is much smaller, is Coprinellus flocculosus. It is shown in the image below, together with it’s spores.

Coprinellus flocculosus
Spores of Coprinellus flocculosus

Footnote May 2011. I found a large patch of these growing nearby a few days ago and picked several kilograms of them. In order to handle them quickly, I decided to chop them and render them down to a soup in a stainless steel pot. It was an expensive pot with a copper insert in the base and I bought it for making jam. They rendered down nicely and I left the pot on the stove overnight, then decanted it into two smaller containers in the morning. The resultant mix had a pleasant, almost sweet smell. However, upon tasting a small sample of soup made from the mix, my senses were soon overcome by an unpleasant metallic taste. Research suggests that this is 1-octene-3-one. I can still taste it after 24 hours and two intervening meals. I have never tasted anything with such a persistant after taste. So that is something to be wary of with this mushroom. I have dried a smaller sample of them, and will investigate their taste with caution.

7 Responses so far »

  1. 1

    Karin Malchus said,

    did the mushrooms interact with the copper perhaps?

    • 2

      morrie2 said,

      Hi Karin,

      The copper was sandwiched between layers of stainless steel and so there was no copper in contact with the contents of the pot. It is just there to improve the heat transfer and prevent hot spots, as stainless is a fairly poor conductor of heat.


  2. 3

    Max Hamilton said,

    Hi Morrie, I’m at Blackheath in the Blue Mountains in NSW. We get a regular crop of what I am 99% sure are shaggy ink caps but that 1% has discouraged me from trying them. Are there any other poisonous types that look similar enough to be confused by? Some of my “shaggy ink caps” are coming up now hence my search and discovery of your site.

    • 4

      morrie2 said,

      Hi Max,

      I am not aware of any look-alikes. There are other species of Coprinus that turn to ink, but none are as large as Coprinus comatus. There is a little bit of regional variation and I have seen them growing both in large clusters and individually.

      Perhaps you can find someone local who can reassure you about the ID? There is no fun in eating something unless you are happy about the identification. That said, these are pretty distinctive. A google image search may help too.

      Good luck


  3. 5

    Carolyn said,

    hi wikipedia ( fount of all knowledge) lists a poisonous lookalike in europe – the magpie mushroom. c. comatus is easily cultivated comercially i see overseas so you can have your own patch easily if you like them. I have also read of a dry sautee method for the more watery mushrooms like boletes – use no oil low heat and sprinkle with a little salt to draw the moisture. might be also good for inkcaps. i haven’t found any yet – hoping hoping

    • 6

      morrie2 said,

      Thanks Carolyn,

      I guess that the Magpie fungus could be confused with Coprinus comatus. Thats one to look out for. The dry saute method is along the same lines of what I mentioned in the post. It was shown to me by a Frenchman when I found those big clusters of them growing at Cradle Mountain. I am sure that you will find some if you keep your eyes peeled, and also put the word out to others to look out for you.

      I have grown a single specimen, so it isn’t impossible, thats for sure. I used straw soaked in calcium nitrate. I still have a culture here somewhere. I’m hoping to put up a growing house this year. hoping…. 🙂


  4. 7

    Trevor McGowan said,

    Coprinus comatus – The shaggy ink cap. These are a light but delicious mushroom. My first experience was while living in the Pine Forest at Ludlow, Western Australia. I ate them and drank some wine and almost immediately vomited. After reading about others similar experience Ive chosen to only eat them before they become shaggy and blue at the base, and have happily consumed then regularly within season.

    So, it may be that when the Ink Cap becomes shaggy there maybe some element preventing our liver from breaking down alcohol and thus rendering it toxic. The toxicity not being the ingredient in the mushroom but rather the alcohol itself not being broken down in the liver.

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