Complexities of Mushroom Identification

Every expert who has a website dedicated to displaying mushroom varieties, or to explaining mushroom characteristics, gets asked to ID mushrooms.

Often the request is something like, "There is a white mushroom in my lawn, can you tell me what it is?". Um... No. Mushrooms are much more difficult to identify than that.

Even when the information given is more complete, identification is a complicated business, and can be either very simple, or almost impossible.

Basically, as far as identification goes, there are three categories of mushrooms:

  1. Those that can be identified Macroscopically. That means, they can be identified fairly reliably by matching features that can be seen, smelled, or tasted.
  2. Those that must be identified Microscopically. This means that you can't tell this one from that one just by looking at them in the field, you need to view certain features under a microscope to be certain.
  3. Those that really can't be easily identified even Microscopically, or which really aren't WORTH trying to identify if your goal is to recognize edible mushrooms. This group includes Little Brown Mushrooms (LBMs), which aren't worth the trouble to identify, and a host of little white, or gray mushrooms. There are literally hundreds or thousands of these, which are not worth the bother to narrow down to even know if they are edible or not, simply because they would not produce enough food if you did gather them, to be worth the risk for our ancestors to have tasted them to see!

SOME mushrooms which can be identified Macroscopically, can be identified by photos. But the photos should include the following for even a halfway reliable ID:

  • Top
  • Underside of the cap (gills or spore surface)
  • Stem
  • Pull one up and take a picture of the stem with the root base
  • Take pictures of immature AND mature ones
  • Take a picture of them growing in their natural habitat.
  • A photo of a spore print would also help, when available.

For a mushroom identification to be certain, all visible features, and a few others, have to match the descriptions.

  • The size and overall appearance of the mushroom.
  • The shape of the cap, sometimes at multiple stages of development.
  • Color of the cap, sometimes moist or dry.
  • The texture of the cap.
  • The shape of the edge of the cap, at various stages of development.
  • The spore surface - gills, ridges, tubes, pores, etc.
  • If it is gilled, the depth of the gills, closeness of the gills, the way the gills attach to the stem, the color of the gills (sometimes at multiple stages of development), the shape of the edge of the gills.
  • The color of the spores.
  • The presence or lack of a ring.
  • The shape and ornamentation on the ring.
  • The shape of the stem.
  • The texture of the stem.
  • The shape and nature of the base of the stem (presence of universal veil remnants, or not, presence of root like threads, or not, presence of fuzzy fungus, or not).
  • The color that it bruises or stains when cut or pressed (if it changes color), the speed at which the color changes, and sometimes, a secondary color because some will bruise one color initially and then it fades or darkens to another color.
  • Whether the bruising or staining is the same color on the cap and the stem, or gills, or the flesh under the cap skin.
  • Whether it grows alone, or in a cluster.
  • The habitat in which it grows, and sometimes the season in which it is fruiting.
  • The smell of the mushroom.
  • In some cases, the taste.

And that is just the basics! With some kinds, there are other features or factors which come into play, and must be observed to correctly ID. And all that is only for those that CAN be identified macroscopically.

Now, there is another thing which makes mushroom identification really tricky. That is, the accuracy of the ID descriptions.

In a sense, there are NO "true" mushroom experts. There is no expert who knows every mushroom. And even those who know many, still rely on guides to match on those that they do not know so well.

When a mushroom is rare, or not commonly harvested, there may be only a single description of it in existence. On the other end of the spectrum, there may be several descriptions, but they may conflict! Sometimes a mycologist gathered a mushroom in the field, described it, and then another mycologist found something in another part of the world, and it sounded pretty much like the other except for one feature (often color), so he just called it the same thing. It may or may NOT be the same thing. Usually it is the same genus, but sometimes not even that!

From those descriptions, we have to identify the thing we just found!

When you have two mushrooms, like Agrocybe Praecox, and Agrocybe Dura, that are so similar that they are classed together in a group, or Lyophyllum Decastes and Lyophyllum Loricatum, which can overlap somewhat in descriptions, or each of which can appear in more than one color, you end up with some confusion regarding the correct ID.

Then there are those like Agaricus Blazei Murrill, and Agaricus Subrufescens, that are often confused because of the way in which they were named and then those names changed, and because they are both almond scented mushrooms, but which are actually two separate mushrooms.

Or Agaricus Brunnescens and Agaricus Bisporus which are classed as two separate mushrooms in older texts, but the SAME mushroom in SOME but not all newer texts, but which ARE actually two separate mushrooms, which have been hybridized so much with each other commercially that many strains out there labeled as one or the other are actually hybrids. (For the record, Brunnescens is thicker, and stains more red than Bisporus and has pinker gills than Bisporus, and Bisporus is a little smaller around, with grayer and darker gills in unopened and barely opened caps.)

And then there is Hypsizygus Ulmarium. The MOST OFTEN misidentified mushroom in the world of amateur mushroom cultivation. This is because a RENOWNED EXPERT misidentified this, packaged it up and sold "Elm Oyster" spawn, and labeled it as Hypsizygus Ulmarium, even though the description for that mushroom is DEFINITELY NOT the mushroom he packaged to sell! Hypsizygus Ulmarium has adnexed gills (they notch inward before they meet the stem, and are not attached to the stem), and they do NOT run down the stem - the stem is short and curved and the cap is round, though it is usually offset some. The Impostor has typical Pleurotus type gills that are decurrent (they run down the stem), a short stem that is not separated from the cap by any distinction, and it has the typical half-trumpet Oyster mushroom shape. If you have purchased Elm Oyster Mushroom Spawn from someone who does not clarify this issue, then you do NOT have Hypsizygus Ulmarium! You have some species or other of Pleurotus (likely Pleurotus Ostreatus var. Florida, since it is a white mushroom that fruits in fairly warm temperatures just as the False Elm Oyster does). In reality, True Elm Oyster fruits in the fall, just as the temperatures drop, whereas the unnamed Pleurotus imposter fruits in the summer, after heavy and sustained rains. Clearly it is NOT Hypsizygus Ulmarium, yet it runs around claiming that name by all but the foragers who seek the real thing, and know it is NOT the same mushroom. The impostor is widely sold as a mushroom that is recommended for cultivation in gardens.

To further complicate matters, some mushrooms hybridize very easily. Agaricus mushrooms do this, so you may have a mushroom that keys to two different species, with just one feature wrong for each ID! Yeah, that happens! The thing that distinguishes this one from that one will be flip-flopped, and it can be very hard knowing what, exactly, it is that you have in your hand! Often this is because when Agaricus mushrooms grow in close proximity to one another, they may hybridize. We have seen this, with Agaricus Placomyces, which grew under a large Hemlock tree. It had black fibrils on the cap, and a chemical smell to it (not edible). A month later, we found some smaller reddish Agaricus mushrooms a few feet away. They had reddish fibrils, and the top of the cap turned pink in the rain (common with several species of Agaricus). Most telling, THIS one had the most delicious almond smell! (Edible, and good.) Two days later, we came back to the same location, and found a new crop of Placomyces growing in the same location they had been in before, but this time they had BLACK fibrils on the top (just like before), but were PINK underneath the black fibrils (it was raining, and the mushrooms were wet). A few feet away (in the opposite direction from the almondy mushrooms) were a few more, which were less pink (sort of blotchy pink on one side only), and a few feet further were some that were still white under the black fibrils. And, the ones that were pink underneath smelled of almonds! The most pink smelled most strongly of almond, the ones without pink did not smell of almonds at all - the blotchy one in the middle was a little chemical and a little almondy. Since then we have seen MANY Agaricus mushrooms that were more like a hybrid than any specific Agaricus, and have concluded that this is normal for many species of Agaricus.

There are also a LOT of amateur mycologists out there that don't realize how closely things must match to be the mushroom they think it is. I cannot tell you the number of times I've Googled a mushroom to see examples, and half the images are obviously NOT the correct mushroom, even though when you go to the page, they are labeled as such. Many times the mis-named mushrooms are on personal blogs, where someone is trying to label the things they've seen on a hike, or in their garden, or while on a nature walk somewhere, but I've also seen a few mislabeled ones on some fairly prestigious sites.

Ok, so sometimes, even when you recognize the mushroom that you have in your hand as being the same as something you have a picture of, you may still have a difficult time putting a name to it, because of a bunch of confusing reasons!

What does all this mean?

It means that some mushrooms are easy to ID. They are so distinctive that you never can make a mistake. A Hawks Wing is a Hawks Wing, and nothing else! Floccularia Luteovirens is similarly unmistakable! You will also NEVER mistake a good sized Giant Puffball.

But others are more complicated. There are tricks for some of them, which can at least be determined for edibility by smell, taste, or color, within a specific genus, but those are the exception. Thankfully, there are enough that are identifiable with a little care, so that you can find many edibles without taking undue risks.

If you want someone else to identify a mushroom for you though, you may find that it is difficult to locate someone willing to assist! When I am asked, I will generally agree to assist, but I will usually make a suggestion, and recommend that the person seeking help clarify the ID with other sources (look up the thing I suggest, and make sure it matches). Often I can only narrow something to a genus by photos, and sometimes not even that. On occasion, the ID is simple, because the mushroom is so distinctive, but that is the exception. Most REAL experts know that identifying by photo is a risky thing, and will not risk the liability of assuring an ID unless they can study specimens in person - especially when they are talking about edible mushrooms.

So as complicated as it can be, the more experience one gains at it, the more you are able to do. Some mushrooms will always be hard to ID. Others will be simple once you know the thing that differentiates them from look-alikes.

But the confusing elements of mistaken ID will crop up again and again. You just have to learn how to recognize when that has happened.

Keep trying though, because in the end, that is what will preserve the good edible mushrooms that are less common.


This Organization and Website are dedicated to the Preservation, Cultivation, and Wise Use of Culinary and Medicinal Mushrooms. We do NOT assist with cultivation or preservation of recreational mushrooms.

Mushrooms may cause allergic reactions in sensitive people. Some mushrooms are more likely to do this than others. Please research possible reactions prior to use. We are not responsible for how you choose to use our information, and do not claim that mushrooms are completely safe to consume.


We do not make any claims as to the efficacy of any mushroom product to treat or prevent any disease or condition. We are not medical professionals and will not provide advice on alternative medicine use for any mushroom. Please consult a doctor or alternative practitioner prior to using any mushroom product for treatment of any disease or illness.


We cannot guarantee that any spawn, spore, or kit product will grow or produce mushrooms. Gardening of any kind is a chancy business, and success depends upon adherence to instructions, and may be influenced by weather, environmental factors, and other controllable and non-controllable factors. As such, we cannot guarantee your success, and advise that if you are uncomfortable with purchasing instructions from us under these terms, that you refrain from purchase.

We do promise to answer your questions, and offer reasonable assistance if needed, and to correct any errors if a mistake is made on our part.

Copyright © 2011-2012. All Rights Reserved.