Mushroom Identification and Confidence

Confidence and Identification: The Devil and the Deep Blue Sea.

The normal question for someone using a mushroom key for the first time is, "but how do you KNOW to choose that one?"

And of course you don't. Know, that is. You guess, in as calculated a way as you can reckon. Are those gills really pink enough? Is that really a gray stain or were your hands dirty when you picked the mushroom? What if its too dry for a Lactarius to bleed milk? And so the game continues.

Perhaps you find yourself with a comfortable similarity between a photo, a written description, and the fungus you hold. And you wonder, "Am I being careful enough? Observant enough? Would someone else be able to better describe the smell of this thing?" And at that point you test your level of confidence. Sure, its Agaricus placomyces; don't expect me to eat that! (your confidence is never tested!)

But on the other hand, those yellow-stainers are A. silvicola, and to prove it, let's try the Hot Butter Test. Now there you must be confident that you got it right. Dine on the wrong Agaricus and spend a bitter night in the water closet, indeed. Willing to bank on your identification job? You want to be SURE, don't you?

Or let's look at the genus Suillus. Some rather unsavory characters in the lot, but mostly acceptable edibles. The punishment for misidentification? A nasty bitter mouthful of Fuscoboletinus, perhaps, but nothing that would put a cramp in your lifestyle. The odds of a successful mushroom hunt and feed are 'mush' better... and the degree of confidence required is a bit less.

Now that we agree on the need for confidence in your ID skills, let's take a look at some to the things that will impact your confidence. The first level that most of us reach is the level of "knowing" a particular species of mushroom and the best advice for beginning mycologists is "go with what you know" Don't try to learn too many species in a single season. Maybe focus your study on some common fungi like Russula or Suillus and try your hand at distinguishing the members of these genera. Focus on distinguishing Fuscoboletinus ochraceoroseus from Suillus cavipes.

Your confidence level is usually higher if you are familiar with the range of biological variation in a species. I've met matsutake mushroom pickers that boasted complete confidence in their ability to discern these prized fungi from any other, and indeed very few non-matsutake make it to the buyer's stations.

But Tricholoma magnivelare is a nondescript, white mushroom. To the casual observer, literally dozens of species of mushroom could be mistaken for it. Yet through all the variability, all the similar species, and all the different habitats it occupies, many people felt they "knew" this mushroom less than a week after their first exposure. Of course, these pickers were hunting for the fungus every day of that week, and had lots of chances to compare. (NOTE: The matsutake also resembles Amanita silvicola, edibility unknown, and A.virosa which is deadly. A high level of confidence in your identification is strongly recommended.).

And the best way to ascertain the identity of an unknown fungus is through the use of a key. Unfortunately, keys are obliged to "key into" certain characteristics which make a fungus unique, rather than trying to impart a holistic impression of the fungus. And unfortunately these characters must be visualized using language, which in itself is a tricky process. Improving the ability to discriminate between fungi is a process, not an event.

It was recently brought to my attention that a number of factors are needed to positively identify a particular mushroom. First, the context of characteristics is important, for example, there are just a small number of Suillus with a veil, but there are plenty of gilled fungi with an annulus of some sort.

Another factor is degree of similarity. There are a heck of a lot of white-spored gilled fungi. An awful lot of them have a sort of brownish cap. It gets much harder to wade through pages of descriptions of similar fungi, and when you get done, you probably don't feel like eating it . Look at how many mushrooms look just like it! Confidence level Zero.

Ask yourself: how many factors do I need to know, and discern, in order to ID this fungus? For something like Suillus tomentosus, perhaps just 3 factors will do: 1. slimy yellow cap and flesh; 2. bright blue stain; and 3. brownish pore mouths. I know of no other fungus that fits these 3 factors, or even comes close. An "easy" ID, with a high degree of confidence.

For another example, let's examine Tricholoma populinum and T.pessundatum. When we found a brown-capped collection of these fungus at the Glacier Institute class last fall and read Arora's description of T. populinum, everyone was convinced we had the right mushroom and ready to cook it up. Then I played the part of wet blanket and read the description of T. pessundatum, and the air went out of our confidence with an almost audible hiss.. the 2 descriptions are nearly identical! The 2 species matched on many counts: brown fibrous cap, white notched gills that stain brown, cucumbery smell, fibrous stem without an annulus, etc. etc. One was edible, the other decidedly toxic. When there are a lot of variables, and many shared with other fungi, it's time to be careful. Eating such a fungus is rarely justifiable.

So we want to reduce the number of factors that can mess up your ID process. One way to do this is to collect diligently. That means keep your collections separate in their own wax paper, never plastic, and keep them cool as quickly and consistently as possible. (It was recently observed that removing fresh morels from refrigeration for even 5 minutes took 2 days off their storage life. If you plan to transport fungi, use baskets which allow the fungi to respire and not be compressed.) This way you can start spore prints in the field, and have greater confidence in your identification. Also, your observations of stain, odor, and habitat details (other fungi or plants, slope, aspect, etc) at the moment of picking may prove critical in identification. Don't be in a hurry to collect, or you may have to throw out unidentifiable material. Trust me. I have to do it all the time.

Hopefully this little column will increase your confidence level in your powers of identification, without inflating it to an unrealistic level. Remember, a mushroom can't make you sick if you don't eat it. It may take a while before you see a certain fungus enough times to recognize it, so don't feel compelled to eat a mushroom the first time you find it. I went for 20 years without eating Clavaria purpurea, although it was one of the first fungi I learned to recognize. By eating a mushroom you are expressing the utmost confidence in your identification. Bon apetit!

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