Aleuria aurantia has the common name “Orange Peel Fungus” because it looks like a discarded orange peel resting on the forest floor (I love mycology; more often than not, names make sense!). The Orange Peel Fungus is a cup fungus (see FFF#032) but is a bit more saucer-shaped than cup-shaped; it is roughly circular and usually has upturned edges. Often, the mushrooms become lobed and somewhat folded in on themselves. This really makes them look like orange peels, which also become wavy if the pieces are large enough. A. aurantia is small to medium-sized with the largest mushrooms growing about as wide as a small orange.
fungi in the phylum Ascomycota
Gyromitra caroliniana, variously called the “Red False Morel,” “Carolina False Morel,” or – my personal favorite – “Big Red,” is a false morel (see FFF#034) that can grow to astounding sizes. It has a reddish-brown cap that is tightly wrinkled, making it look very similar to true morels (see FFF#033). The easiest way to differentiate Big Red from true morels is to cut it in half; true morels have a central hollow chamber while false morels like Big Red are solid or have lots of small chambers. Big Red gets its common name from its cap color and the fact that it routinely produces mushrooms that weigh over three pounds.
Ergot Alkaloids (EAs) belong to a large class of mycotoxins. They are primarily produced by fungi in the genera Claviceps and Epichloë, although Claviceps purpurea is responsible for most of the impacts on humans. EAs are most common in rye, but can be found in any cereal grain. The toxins were a significant problem in the middle ages, but modern agricultural techniques mean that exposure to enough EAs to cause symptoms is extremely rare.1,2 Sources Many fungi produce ergot alkaloids in many different plant hosts. Humans are impacted most by species of Claviceps, which infect seeds of grasses. The most problematic species is C. purpurea (see FFF#061), which infects rye. A variety of other species infect cereal grains but cause less contamination. Livestock can be sickened by infected grain or by ergot alkaloids produced by endophytes in pasture grasses, most notably by Epichloë coenophiala.1–3 This post focuses on Claviceps and...
Unlike most other mycotoxins found in food, the ochratoxins are primarily produced during food storage. Fungi in the genera Aspergillus and Penicillium are common molds that decompose a variety of foods, from grains to coffee to grapes. In the process, many of those fungi produce ochratoxins, which can damage the kidneys and cause cancer in many animals. Ochratoxins presumably impact humans the same way, but researchers have so far been unable to directly link ochratoxins to any human disease. This is probably because human consumption of ochratoxins is usually very low.
Zearalenone is a fascinating mycotoxin produced by Fusarium species. It is the only mycotoxin that mimics the effects of the hormone estrogen. In high doses, it causes sexual organs to develop incorrectly. Pigs are the most susceptible animals and suffer estrogenism and vulvovaginitis when exposed to high levels of zearalenone. The toxin is present in many grain-based foods intended for human consumption, but usually at very low levels. As a result, zearalenone is generally harmless to humans.
Humans have very little to worry about from fumonisins, mycotoxins produced by Fusarium fungi that cause Fusarium ear rot disease of corn (maize). The toxins are linked with esophageal cancer, but scientists cannot prove that they cause cancer. However, fumonisins are a major problem for horses and pigs. In horses, the toxins cause liquefaction of the brain tissue, while in pigs they cause the lungs to fill with water.
Deoxynivalenol (DON) is a toxin found in grains infected with the fungus Fusarium graminearum and other Fusarium species. It is often called “vomitoxin” because it primarily causes vomiting in humans and livestock. Its long-term effects are mild, but it is still a very important mycotoxin because it is the most common mycotoxin found in food.
Fungi produce innumerable “mycotoxins” – compounds that are toxic to humans. In mushrooms, these cause symptoms ranging from gastrointestinal upset to death (see FFF#091–100 for more). Although these are of significant concern to mushroom hunters, their impact is relatively small. The most significant mycotoxins in terms of the number of people affected are produced by molds that naturally grow on food. Over the next few weeks, I will discuss some of the most problematic food-borne mycotoxins. Topping that list are the aflatoxins, which cause liver cancer and are especially problematic for people in developing nations.
In late October, it is not unusual to see Halloween decorations featuring bony fingers reaching up out of a grave. The natural world has its own version of this: Xylaria polymorpha, commonly known as Dead Man’s Fingers. This macabre name is an apt description of the mushrooms, which resemble burnt and dried out fingers reaching out of the ground to grab unwitting passers-by and drag them down into the depths of the earth. You can find these morbid ascomycetes on rotting logs at pretty much any time of the year.
Tolypocladium ophioglossoides (also called Cordyceps ophioglossoides and Elaphocordyceps ophioglossoides) is a fun little mushroom to find, but you have to be paying attention to enjoy it. Unlike most fungi that were placed in Cordyceps, which were insect parasites, T. ophioglossoides – commonly known as the “Golden Thread Cordyceps” (even though it is no longer in that genus) – attacks other fungi. Specifically, it parasitizes truffles in the genus Elaphomyces. If you can spot this tiny brown/black mushroom, make sure to dig it up carefully and follow the golden thread that attaches the mushroom to its truffle host.