Identifying a field mushroom


Disclaimer  :  These notes are provided as a guide only.  While every attempt has been made to try to assist in the identification, the risk of eating any wild mushroom rests with the individual and I do not accept  any responsibility for consequences  that may arise from the action of anyone eating wild mushrooms.  See also the Ag department notes, Perth.  and inedibles and lookalikes


The fungus that we know in Australia as a field mushroom is a member of the genus Agaricus.  This is a large genus with a single ancestor (monophyletic) and within the genus is a number of sections each containing a range of species.  While it is tempting to try to assign a species name to any mushroom that you might find, this can be difficult in Australia because many of the species are undescribed or if they are described they aren’t reported in popular guide books.  In addition, it might require the use of a microscope and other detailed analysis.   For our purposes though, it isn’t important to have a name; edibility can be determined by features that can be simply observed.  Our main objectives are:

  • make sure we have an Agaricus
  • Make sure it is not in the section Xanthodermatei

Examples of some well known members of the Agaricus genus are:

Agaricus bisporus – the classic small supermarket mushroom

Agaricus bitorquis – marketed as a larger form of supermarket mushroom

Agaricus avensis – the almond mushroom or horse mushroom.

Agaricus campestris – the classic if oft mis-identified field mushroom.

This list of features has been put together to assist the average person to identify an edible field mushroom.

1.  Cap colour and texture

The cap of the edible Agaricus species varies from white though dun and on to a slightly pinkish colour in species like A.  sylvaticus.  The cap may be slightly scaley, and may be cracked.  It is always dry and is never slimy to the touch.  Both the colour and texture of the cap are influenced by the environmental conditions as well as the genetics.

Any mushroom with any hint of green in the cap colour should be rejected as this is the colour of the deadly Amanita phalloides.

 top of small field mushroom, typical of those found in lawns (Dave Freer)

top of large field mushroom, similar to supermarket field mushroom (Dave Freer)

top of Agaricus arvenis, showing scales

A forest mushroom, showing red tones on the top

Top of Agaricus bitorquis.  A clean off-white, with undulations

A horse mushroom from the Riverina district of NSW.  Note scales.

A mushroom from a backyard in Penhurst, Victoria, showing some radiating spots.

A mushroom from Digby in Victoria, showing red/brown central region and radiating scales.

2.  Gill colour

The gill colour may vary from brown to pink or off-white in the young mushroom, but it will always darken to a dark brown in a mature specimen.  ‘Not black, but dark brown. Never eat a mushroom with white gills.  This eliminates the poisonous Amanita and Chlorophyllum.

Pink colour of immature specimen of  a small field mushroom.  Picture courtesy of Dave Freer.


3.  Spore print

The spore print is always dark brown.  Not pink, not rusty, not black or purple or white.  Dark brown only.

How do we take a spore print?  Easy.  Place the mushroom, or a piece of it, on a piece of waxed paper and place a glass over the top, with the edge of the jar just propped up by a matchstick or something similar to allow water vapour to escape.  Place in a position away from draughts, overnight.

A simple setup for taking spore print

A spore print of an Agaricus species

4.  The stem snaps away from the cap

The stem of an Agaricus has a texture that comprises a bundle of stringy cells running axially.  The cap has a different texture.  At the point of the junction of these two textures, there is  region where the two will break apart cleanly.  Try this for yourself with a supermarket mushroom.  Note in this mushroom the dark gill colour.

The point of separation should be between the top of the stem and the flesh of the cap.  In some species the stem appears to break away cleanly, but close inspection will show that there is a piece of the flesh from the cap attached to the stem and the position of the separation is actually between the surface of the cap and the flesh of the cap.

This test serves to separate Agaricus from members of the family Cortinaraceae, such as Hebeloma, Inocybe, Cortinarius and Galerina, some of which are seriously poisonous.

5.  Smell

Field mushrooms have a distinctive smell that is either ‘mushroomy’  due to a chemical called octenal, or almond/aniseed due to the presence of benzyl alcohol and benzaldehyde.

If the mushroom has a smell of phenol, which is the smell of India ink, or phenyl disinfectant, coal tar soap, creosote or sometimes described as ‘chemical’, then it should be rejected.  Another common product that has the phenol smell is wheelie bin cleaner.  It contains cresols, which are related and smell the same.   Interestingly, and I don’t know why, at high dilutions wheelie bin cleaner smells like clag glue.

If in doubt,  there are two approaches you can take;  1) put the mushroom in a plastic bag for 15 minutes and then sniff the contents or  2) cook a piece of the suspect mushroom.  The bad smell will become more apparent if there is phenol present as will the almond smell. If you can’t reliably and comfortably identify the smell, preferably with confirmation from someone else, then you should reject the mushroom.

It is often reported that some people can tolerate eating mushrooms that contain phenol.  The only stories I have heard of such poisonings have involved the whole group of consumers.  I suspect that the truth is that some people report eating yellow staining mushrooms without ill effect, but they have in fact consumed one of the arvenses group rather than one that contains phenol.

Why is phenol a problem and benzaldehyde isn’t?   Because phenol causes acute irritation of the gastrointestinal tract.  This can cause distress and vomiting, but it will pass and will not leave any permanent damage.  Benzaldehyde is a natural product that is a component of almond essence that is used in making marzipan and is without any toxic effects at the doses involved in mushroom consumption. Similarly, benzyl alcohol has low toxicity.

Some poisonous species contain hydroquinone as well as phenol.  This too can also cause gastric upsets. In these ones, both the phenol smell and the yellow colour are not as intense.  The smell should be determined on a fresh specimen at the base of the stem.

6.  Colour of cut or bruised flesh

The colour of the cut or bruised flesh may be brown or red or yellow, or there may be no change in colour at all.  Here for example is an edible mushroom, Agaricus bitorquis, which is showing red on a cut piece.  Photo courtesy of Dave Freer.

Brown or red bruising is ok.   A yellow colour may be ok or it may indicate Agaricus xanthodermis, which will cause stomach upsets.  There is much confusion about this.  The yellow colour is an indicator of  A. xanthodermus, which contains phenol, but it does not necessarily indicate an indedible mushroom.   For a diagnosis of an indedible yellow staining mushroom, one needs to have the yellow stain in combination with a phenol smell, as mentioned above. Another term for yellow staining is ‘flavescent’.

The place to determine both the colour and the smell is the base of the stem.  Both features are less prominent in other regions of the mushroom. Don’t be shy, really squash it to get the smell.

Another feature of the yellow staining inedible species is that the yellow colour changes to brown over about an hour.  The yellow colour also intensifies with cooking.  Another test is that the colour intensifies and stays permanent in response to a drop of a 10% solution of potassium hydroxide or the more easily obtained sodium hydroxide which does the same thing. Here is a picture of a mushroom that has been tested with sodium hydroxide.

yellow stain with caustic

Yellow stain enhanced with 10% sodium hydroxide solution



7. Substrate

Field mushrooms will always be found growing from some kind of soil.   They never grow directly from wood and they do not  grow in the middle of cow pats.  There are some deadly species like Galerina that grow from wood and if it is growing from a cow pat, there is a good chance that it is the notorius hallucinogenic ‘gold top’, on the east coast at least.  They do not tend to grow from wood chip or bark mulch either.

Don’t pick and eat mushrooms that grow beside highways or other places where they may have accumulated things like heavy metals or other potentially toxic things.  Mushrooms can be quite good at gathering these things.

8.  Cap shape

Mushrooms of the section Xanthodermatei, the yellow-staining, phenol containing species tend to have a flat top when juvenile, sometimes continuing to when they are fully grown.  They are often described as having a ‘boxy’ shape.

This, however is not exclusive to this section.  There are many other species that have a similar flat top, and the classic example is Agaricus augustus, known in the US in particular as The Prince, and highly prized as an edible.  So the flat top has limited value as a diagnostic tool.  Sometimes people declare mushrooms to be yellow strainers and therefore inedible based on shape alone without even testing for a yellow stain and smell.  I suggest taking a more thorough approach as outlined above.

9. Tasting

If you are eating an Agaricus that you have never eaten before, try out a small piece first. Sometimes we can be allergic to mushrooms for no apparent reason.   If it tastes horrible, don’t eat it!  This has happened to me with something I expected to taste good.   If you have not experienced any ill effects by the next day, then you can move forward to eating a larger quantity.

Whatever you do, don’t gulp down a huge meal of something that you are unfamiliar with.

10.  One final thing

If, after reading all of the above, you are still not sure, then there is an old mushroom gatherers maxim that applies:

If in doubt – chuck it out

Peter Donecker

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Calvatia fragilis – another edible puffball

While driving around in April, I noticed for the first time this year some rather large puffballs growing around the place.  Here is what they looked like.


Calvatia fragilis

When cut open, these revealed a firm white flesh with a pleasant mushroom smell.  They lacked a ‘sterile base’ which is the bit at the bottom close to the attachment point to the ground.  The lizard skin pattern was also distinctive.  On standing, they developed a purple spore mass.  All of these factors together led me to identify them as Calvatia fragilis, which was subsequently confirmed by DNA analysis (97% AJ684871).

The picture below shows the specimen torn open.  There is a slight yellowing when it is bruised. It has a distinct skin.

Calvatia fragilis torn open

Calvatia fragilis torn open

The next picture shows another view of the surface of the puffball.

Surface of Calvatia fragilis

Surface of Calvatia fragilis

Some people say that all white puffballs in Australia are edible.   This is not true as many years ago I found a massive white puffball growing next to a mulga tree in Hopetoun that had an extremely unpleasant smell.  When I heated some up it caused us to evacuate the kitchen!

Calvatia fragilis is edible though and I sliced this one and fried it in butter.  The taste reminded me a little of eggs.

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Rhizopogon – a taxonomic challenge

A walk in a pine plantation in WA during winter will often reveal a truffle-like fungus lying on the top of the ground or sometimes almost buried.


Rhizopogon pseudoroseolus

This is Rhizopogon, introduced with the pine trees and a very effective fungus for assisting the pines to grow.  The mycelium from fungi such as these acts as an extension of the roots of the trees, drawing in nutrients that would otherwise be unavailable to the trees.

Many sources report that the species occurring here are Rhizopogon luteolus but DNA results on the specimen pictured above match R. pseudoroseolus (GQ267483).  This species, an introduction from the USA is also very common in New Zealand, though the appearance does not appear to match either the image nor the key published by Jerry Cooper of the Fungal Network of New Zealand. There are many different species, lots of variability and many published revisions of this genus so it does make identification difficult.

In Japan, a member of this genus, Rhizopogon roseolus is much prized as a food where is it known as Shoro.  The Kiwis, always much more proactive on these matters than we are, have done some comparisons on the species growing in New Zealand with those in Japan and have gone so far as introducing the Japanese species into NZ as a potential agricultural product.

This is not an easy fungus to identify visually and there is sparse information about edibility.  My friend Jsun has eaten a species that grows in Queensland and while visiting here he pickled some that I had collected.  These are shown in the picture below.  He has selected specimens that were firm and had a white interior when cut in half. When pickled, the outside became quite distinctly reddish.


Pickled Rhizopogon pseudoroseolus

I have eaten small quantities of these and must say that they are rather bland. Jsun reports that he likes to add them to stews and so forth and that they soak up the flavor of the dish.

See also:

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Laetiporus portentosus -White punk, poor tucker indeed

There have been many reports from the times of early European settlement, all from Tasmania, of the Aboriginal people eating a white’ punk’ growing on trees.  It has been widely assumed that this is Laetiporus portentosus, formerly known as Piptoporus portentosus.

This June I chanced upon a specimen of this lying on the ground in Bridgetown.  It was quite a massive thing, weighing several kilos and it was saturated with water.  That is why I assume was on the ground, having fallen from its position because of its weight.  Here it is sitting on my dining room table.

Laetiporus portentosus desk

Fallen Laetiporus portentosus on table


Here is another shot of it, this time showing the inside after I had cut it open with great difficulty.  I don’t think this would have been possible with primitive tools.

Laetiporus portentosus cut

Laetiporus portentosus cut open

You can see that the inside looks sort of cottony.  In fact it more closely resembles polystyrene in texture.  An attempt to eat a small piece of it revealed that it was about as edible as polystyrene too.  Not even in an emergency could anyone possibly eat and digest this fungus.  Perhaps the story is different with very small specimens but I am doubtful.

It is quite difficult to get a picture of one of these in-situ on a tree because they tend to grow quite high up.  I was lucky enough to spot one by a road cutting near Donnybrook that enabled me to scramble up and take a picture with my phone.  Here it is.

laetiporus donnybrook

Laetiporus portentosus in situ

The fact that these are relatively few and far between and so high up on the trees is further evidence against them being used as food.

It is however widely reported that they were used as tinder and to carry fire.  Some experiments revealed that a dried specimen could be ignited very readily and that it would smolder for a long time.  By judicious control of the fire front on a smoldering specimen it could easily be kept aglow for hours.  Uncontrolled burning of half a specimen lasted about 40 minutes.  I made a short video of a small piece smoldering after it had been ignited. A still from that video is shown below.

laetipurus glowing

A piece of Laetiporus portentosus smoldering


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Macrolepiota clelandii – not for the moment

This is a common mushroom around the karri forest and other places during the early part of the rainy season.  It used to be listed as Macrolepiota konradii in guides until quite recently until Else Vellinga renamed the group in 2002.  Almost all sources list this as edible, except for Tony Young who says that this Australian species is of unknown toxicity.


Macrolepiota clelandii

Its edibility seems to be  based on the fact that is was thought to be the same as the edible M. konradii from Europe.  Since this is now thrown into doubt, if not thrown out completely, I think it a wise precaution to avoid it.  Besides which, I have a general aversion to Chlorophyllum and Macrolepiota due to the fact that they sometimes cause inexplicable gastric distress.  I am sure that some people do eat or have eaten these though, so I list it here for completeness.

Here is a picture of the top surface.


Macrolepiota clelandii top surface

It is a rather pretty and delicate mushroom that will sometimes spring up in the oddest places.   I had one come up once half way down a post hole that I had left open. The specimen pictured is about 150mm high with a cap 100mm across.  That is a typical size.  They don’t occur as a small mushroom.  In fact, there are some small Lepiootas that look rather similar and some Lepiotas are deadly.

So I will abstain for the moment.

Update: August 2016

My fellow blogger Jsun and I picked some of these during July and he was able to confirm that they were the same as those he had eaten in the east.  I watched him cook and eat some and being thus encouraged I had a small portion myself.  I am now much more confident about these.   One thing he pointed out to me was the ‘snakeskin’ pattern on the stem which also flares out at the base.



Snakeskin pattern on stem

The ring or annulus is quite distinctive also,  breaking up in radial splits and being attached at first, but moveable with some encouragement.

macrolepiota ring

Detail of ring

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Leucoagaricus leucothites -with caution


Leucoagaricus leucothites



Leucoagaricus leucothites was formerly called Leucoagaricus naucinus and with the state of flux in taxonomy at present, it might have another name next year.  It is a mushroom of worldwide distribution, widely known as an edible species but often recommended as a species to be avoided because it shares so many features with a couple of deadly Amanitas. For this reason nobody should attempt to eat these unless they are completely confident in being able to distinguish an Amanita.

I spotted the specimens above by the side of the road, which is a common place to find them.  The caps are bright white with a satin texture.  The shape of the large specimen in the picture is characteristic of this species.   The underside features a hollow stem that widens a little at the base, but does not have a sac or volva like Amanita or Volvopluteus.  The gills are at first white but darken a little at maturity. The spore print is bright white.

It is always a little scary eating something new but even more so when it is something with white gills and a white spore print.   Nevertheless, after much checking and re-checking I fried some up and did a taste test.  From descriptions elsewhere I had expected something more; it tasted just like Volvopluteus gloiocephalus.  The mature specimen even looks a little like Volvopluteus.

One can only wonder how species like this manage to spread so far and wide.   Apparently the spores of this one germinate very readily in a wide range of media so perhaps that has something to do with it.  Anyway, another of our introduced species that is edible for what it is worth.

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Volvopluteus gloiocephala – a common roadside species

I was doing some research and maintenance today when I realised that I didn’t have a blog entry for this mushroom, though it is a very common one that I have been eating for 30 years.  Perhaps I accidentally deleted it. It used to be known as Volvariella speciosa until quite recently when some DNA studies indicated that it should be placed in a new grouping.

If you are driving around Perth in wintertime, you will see this everywhere growing on roadside woodchip mulch.  It also occurs on waste ground.  It is not generally a good idea to eat mushrooms that grow by roadsides as they can accumulate various toxins.  However, these are so widespread that it should be possible locate some that are growing in a safe spot.

One of the important things to know about this species is that it looks very similar to an Amanita.  On the east coast, people have died after picking and eating the deadly Amanita phalloides, mistaking them for Volvariella volvaceae, the paddy straw mushroom of Southeast Asia and Queensland.  It would be very easy to make a similar fatal mistake here in the West, confusing Volvopluteus with other species of Amanita.  I have seen the two growing very close together and they are nearly impossible to tell apart.  It is only when the mushroom reaches maturity and the rusty orange gills become evident that Volvopluteus becomes easy to identify.

Now for some pictures.  I had to recover these from an old computer in the shed that I first bought in 2003.  That was an interesting exercise in itself, requiring removal of the hard drive and taking it to the computer shop.

This first picture shows the mushroom just as it is emerging.  It looks just like the hard boiled egg that I have placed beside it.


Emerging mushroom beside a boiled egg

As it grows, it begins to take on some shape.  You can clearly see the sac or volva at the base.


Beginning to grow, showing volva



At maturity, it takes on a classic shape.

two volvariellas

Typical Volvopluteus gloiocephala at maturity


The gills, which are white at first, take on a rusty orange colour at maturity.  It is at this stage that identification is most accurate.

vovariella pair

Mature specimens, showing gills


This mushroom has an unusual and distinctive taste.  I often cook it in a sauce that I add to silverbeet and serve it with roast chicken.

All of my numerous attempts to cultivate this mushroom have failed, resulting in a slimy bacterial looking mess.  It is possible, as others have done it, so I will give it another go next time I find it, with my more recently installed laminar flow hood.


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Clitocybe (Lepista) nuda – The Wood Blewit – a surprise

Someone who is enthusiastic about mushrooms like I am will let their friends know about it and when they spot something that you might be interested in, they will tell you about it.  So it was the other day when we were looking at a house for sale in Bridgetown.  My friends were in a small section of yard where someone had dumped some grass clippings.  Spotting some mushrooms, they called me over.   To my amazement, there was a cluster of Clitocybe nuda, perhaps more widely known as Lepista nuda, or the Wood Blewit.  This is a very cosmopolitan and widely eaten mushroom, that requires cooking before consumption.

This mushroom is an introduction to Australia and is quite common on the east coast where I frequently see pictures of specimens that others have found, but having never seen it in Western Australia, I assumed that it did not occur here, like several other species more common in the east. Edit: I have subsequently found that there is a single record from the Perth region from 1981, but I cannot access the record for some reason. Too old perhaps.

The particular specimens that were growing from the grass clippings were rather aged, though there were some new buttons starting up.   In the image below you can see both.

Clitocybe nuda in grass clippings.

Clitocybe nuda in grass clippings.

I have overturned the mature specimens to show the purple colour of the gills.   You can just see a purple button emerging at about 5:30. (sort of, sorry about the image quality, I had to use my phone). Here is a close-up of one of the buttons in the pile.

Button of Clitocybe nuda

Because these specimens were too old, it was not possible to consider eating them.   I am currently in the process if trying to get a clone going from one of those little buttons though.

Edit.  I visited the site about a week later and the little button had grown into a small but fully formed mushroom.   I think that these are some of the prettiest mushrooms around.  When cut, the stem showed a purple colour similar to the gills.


There are some other purple mushrooms around that one might easily mistake for this one.   These belong to the genus Cortinarius and it would be most unwise to eat any of them.   The one the springs immediately to mind is Cortinarius archeri. There are two main differences between Cortinarius and this mushroom.  The first is that Cortinarius always grows in association with a tree.  It is mycorrhizal.  These specimens are quite clearly growing from the grass clippings where the mycelium could be seen reaching down into the pile, however.  The second is that Cortinarius has a rusty orange spore print (see below).  These had a rather pale spore print (it was a very faint print because of the age) but is was clearly not rusty orange.  The orange colour of Cortinarius can also be seen in the gills as they mature and as a deposit on the stem, where the remains of a membrane is evident.  Prue also talks about this type of confusion on her blog. She is possibly referring to Cortinarius austroviolaceus which is the Australian version of C. violaceus.


Cortinarius archeri

Another couple of purple capped mushrooms are Leucopaxillus lilacinus and Russula clelandii.

Though I haven’t eaten this one, my friend Fiona  over at WhereFishSing has reported her experience with it, which anyone interested might like to read.

Now that I know that these are around, I am hoping to find more of them.  And if anyone comes across some little purple button mushrooms growing in their compost or grass clippings, keep and eye on them and please let me know about it.

If I manage to get this into culture, I will post some further images.

As a footnote, there are several other species related to this one growing on the east coast though they are smaller.

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