Category: Fungus Fact

Sphaerobolus ingoldii 0

#122: Sphaerobolus stellatus, the Artillery Fungus

Sphaerobolus stellatus has one of the most unusual spore dispersal mechanisms: its base pops up and quickly flings a glob of spores into the air. The fungus forms tiny (no more than 3mm across) star-shaped mushrooms in mulch, which can cause problems for homeowners when the spore globs glue themselves to cars, siding, and the like. S. stellatus’s unique spore dispersal strategy has resulted in a variety of common names, including: “Artillery Fungus,” “Cannonball Fungus,” “Cannon Fungus,” “Sphere Thrower” (which is a literal translation of its Latin name), and “Shotgun Fungus.”

Ganoderma applanatum 0

#070: Ganoderma applanatum, The Artist’s Conk

Ganoderma applanatum is unique among fungi in that it is primarily used by humans as an artistic medium. This large, woody bracket fungus features a mostly flat white pore surface that immediately stains brown when handled. Because of this, the mushroom readily becomes a natural canvas for an artist. By lightly scratching the pore surface, an artist can produce beautiful sketches without using a pen, pencil, or paint. The pores stop growing once the mushroom is removed from its substrate, so the stains remain on the pore surface. Conks produced by G. applanatum are woody and therefore decay very slowly. As a result, artwork produced on the Artist’s Conk can last for many years when dried and kept indoors.1,2 Description Ganoderma applanatum forms large conks, which are fan-shaped polypore mushrooms that grow shelf-like from dead logs. Conks are also known as bracket mushrooms or shelf mushrooms. The conks produced by...

207: Ergot Alkaloids 0

207: Ergot Alkaloids

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...

Amanita muscaria 0

#069: Amanita muscaria, Part 1: The Type Mushroom

You are undoubtedly familiar with this mushroom, even if you recognize neither its scientific name, Amanita muscaria, nor its common name, “The Fly Agaric.” If the word “mushroom” does not immediately bring this fungus to mind, then the word “toadstool” probably does. You have certainly encountered A. muscaria’s distinctive red cap with white spots in a variety of visual art forms. This toadstool frequently pops up in paintings, cartoons, video games, movies, and decorations. Essentially, A. muscaria is the default mushroom that people (in Western societies, anyway) think of when they hear the word “mushroom” – the type specimen for mushrooms, if you will. This is probably best illustrated by the Wikipedia page for “Mushroom,” which features a prominent picture of the photogenic Fly Agaric. Morphology Amanita muscaria produces large, umbrella-shaped agaric mushrooms with a circular, brightly colored pileus and a central, white stipe. The pileus ranges in size from...

Ochratoxin-producing molds 0

#206: Ochratoxins

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.

Fusarium molds 0

#205: Zearalenone

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.

Fusarium verticillioides spores 0

#204: Fumonisins

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.

Trametes versicolor 0

#065: Trametes versicolor, The Turkey Tail

In honor of the recent Thanksgiving holiday, I chose to rework this post on the Turkey Tail. I will continue discussing mycotoxins next week. It is easy to see why Trametes versicolor is commonly called the “Turkey Tail”: the upper surface of the fan-shaped polypore sports rings of color that vary from gray to brown to reddish-orange. In fresh specimens, the edge of the mushroom is white, making it look remarkably like the displayed tail of a wild turkey. T. versicolor is a very common decomposer and produces mushrooms that are visible all year, so you can probably find it the next time you walk through the woods.

Fusarium head blight 1

#203: Deoxynivalenol

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.

Aspergillus flavus 2

#202: Aflatoxins

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.