The only sure way to distinguish between morels and false morels is to have years of experience under your belt. That said, however, there are easily recognized differences between them, and I see no good reason for anyone to get confused.
Rule Number One: When in doubt, throw it out!
If you are not 100 percent sure your mushroom is a morel, why would you even think about eating it?
Rule Number Two: If it ain’t hollow, don’t swallow!
Morels are hollow. Slice open a black, yellow, or half-free morel and you will find only air (and bugs, if you haven’t cleaned it), from top to bottom. Slice open a false morel, and you’ll find mushroom flesh. Sometimes the flesh of a false morel is interspersed with air pockets, creating a “chambered” effect–but there is flesh present. Consequently, false morels weigh more than morels. If you hear someone bragging about how much a morel weighed before he ate it, you are speaking to an idiot.
Rule Number Three: If it’s wavy, don’t make it gravy!
The caps of false morels are often wavy, rather than pitted. The pits on morels are not, on very close inspection, symmetrical, but they are very regular when compared to the lobed, wavy, brain-like structure of the false morel. Here, by the way, we encounter a problem with some of the common names for morels: “brain mushrooms” and “sponge mushrooms.” Do not rely on what you picture from these common names! False morels are better described as “brain-like” than morels, and either kind of mushroom could conceivably be described as “sponge-like.”
Rule Number Four: If it’s reddish, you could be dead-ish!
False morels frequently (though not always!) have reddish brown shades. I have seen yellow morels develop red stains, especially in age (the stain usually begins as a stripe on the stem and then grows), and when morels are growing under pine. So, this rule might eliminate some good-eating morels. But it is more likely to eliminate false morels. Don’t rely on this rule (or any of the rules, for that matter) alone!
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Kuo, M. (2001). Edibility rules for morels. Retrieved from the MushroomExpert.Com Web site