At this time of year, many people are foraging for (true) morels to eat. Also found fruiting in the woods right now are false morels – species of morels that contain varying levels of the chemical monomethyl hydrazine (MMH). MMH causes vomiting, dizziness, diarrhea, and sometimes death. Some false morel species contain very little, others contain lethal amounts. MMH levels also vary among geographic regions within a single species. While they are harvested in certain parts of the U.S., nobody knows with any certainty how toxic any false morel will be in any location. Thus, it is important to be able to tell them apart from true morels.
First, make note of the cap shape. False morels tend to be more rounded; true morel caps more cylindrical. Most false caps are “wavy” or “lobed.” They appear to be bulging outwards. True morels have a more uniformly shaped cap with pits or ridges; they appear to be pitted inwards rather than bulging. Also, the cap of the false mushroom typically hangs freely from the stem. A true morel has a cap that is usually attached to the stem. Lastly, if you slice a true morel open from top to bottom it will be hollow inside. A false one will usually be filled with wispy cotton-like fibers or chunks of tissue. (Thanks to Ginny Barlow for photo op.)