HIDDEN GIANT: A small outcropping of honey mushrooms on the surface hide the largest known organism on Earth, a fungus infesting the woods of eastern Oregon.
Image: USDA FOREST SERVICE, PACIFIC NORTHWEST RESEARCH STATION
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Next time you purchase white button mushrooms at the grocery store, just remember, they may be cute and bite-size but they have a relative out west that occupies some 2,384 acres (965 hectares) of soil in Oregon's Blue Mountains. Put another way, this humongous fungus would encompass 1,665 football fields, or nearly four square miles (10 square kilometers) of turf.
The discovery of this giant Armillaria ostoyae in 1998 heralded a new record holder for the title of the world's largest known organism, believed by most to be the 110-foot- (33.5-meter-) long, 200-ton blue whale. Based on its current growth rate, the fungus is estimated to be 2,400 years old but could be as ancient as 8,650 years, which would earn it a place among the oldest living organisms as well.
A team of forestry scientists discovered the giant after setting out to map the population of this pathogenic fungus in eastern Oregon. The team paired fungal samples in petri dishes to see if they fused (see photo below), a sign that they were from the same genetic individual, and used DNA fingerprinting to determine where one individual fungus ended.
This one, A. ostoyae, causes Armillaria root disease, which kills swaths of conifers in many parts of the U.S. and Canada. The fungus primarily grows along tree roots via hyphae, fine filaments that mat together and excrete digestive enzymes. But Armillaria has the unique ability to extend rhizomorphs, flat shoestringlike structures, that bridge gaps between food sources and expand the fungus's sweeping perimeter ever more.
A combination of good genes and a stable environment has allowed this particularly ginormous fungus to continue its creeping existence over the past millennia. "These are very strange organisms to our anthropocentric way of thinking," says biochemist Myron Smith of Carleton University in Ottawa, Ontario. An Armillaria individual consists of a network of hyphae, he explains. "Collectively, this network is called the mycelium and is of an indefinite shape and size."
All fungi in the Armillaria genus are known as honey mushrooms, for the yellow-capped and sweet fruiting bodies they produce. Some varieties share this penchant for monstrosity but are more benign in nature. In fact the very first massive fungus discovered in 1992—a 37-acre (15-hectare) Armillaria bulbosa, which was later renamed Armillaria gallica—is annually celebrated at a "fungus fest" in the nearby town of Crystal Falls, Mich.
Myron Smith was a PhD candidate in botany at the University of Toronto when he and colleagues discovered this exclusive fungus in the hardwood forests near Crystal Falls. "This was kind of a side project," Smith recalls. "We were looking at the boundaries of [fungal] individuals using genetic tests and the first year we didn't find the edge."
Next, the microbiologists developed a new way to tell an individual apart from a group of closely related siblings using a battery of molecular genetic techniques. The major test compared fungal genes for telltale signs of inbreeding, where heterozygous strips of DNA become homozygous. That's when they realized they had struck it big. The individual Armillaria bulbosa they found weighed over 100 tons (90.7 metric tons) and was roughly 1,500 years old.
"People had ideas that maybe they were big but nobody had any idea they were that big," says Tom Volk, a biology professor at the University of Wisconsin–La Crosse. "Well it's certainly the biggest publicity that mycology is going to get—maybe ever."
Soon afterward, the discovery of an even bigger fungus in southwestern Washington was announced by Terry Shaw, then in Colorado with the U.S. Forest Service (USFS), and Ken Russell, a forest pathologist at Washington State Department of Natural Resources, in 1992. Their fungus, a specimen of Armillaria ostoyae, covered about 1,500 acres (600 hectares) or 2.5 square miles (6.5 square kilometers). And in 2003 Catherine Parks of the USFS in Oregon and her colleagues published their discovery of the current behemoth 2,384-acre Armillaria ostoyae.
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16 Comments
Add CommentAccording to Wiki (http://en.wikipedia.org/wiki/Largest_organism), the largest undisputed single organism is an aspen tree named Pando. This fungus, while genetically indentical throughout, has not been proven to be anything more than a colony of clones.
Reply | Report Abuse | Link to thisyour scientific American newsletter really helped me to enhance my knowledge in every field.I am really grateful to you.
Reply | Report Abuse | Link to thisThank you very much
This mushroom is pushing the bounds of classification. You are using Wikipedia to validate the studies here? For a while now, I have seen this observation quoted in many scientific books. Maybe when the general public catches on to whats happening in this field, someone will get around to changing the Wikipedia page.
Reply | Report Abuse | Link to thisThe nature of individuality might work well for Vertebrates, you act on the snout of a blue whale and you will get a very quick reaction in the tail. To have that sort of action and reaction along the mycillia over several miles would be a lot harder to demonstrate.
Reply | Report Abuse | Link to thisEven to set up a stimulus or electro chemical wave and read it at a distance would be interesting, but if there is no relationship from one side of the organism to the other the situation is less interesting that it first appears.
Paul Stamets cites '6 ways mushrooms can save the world,' and though he does not invoke psychoactive mushrooms as Roland Griffiths of Johns Hopkins may, nonetheless makes a persuasive argument. Think it can be checked on a TED talk, somewhere...
Reply | Report Abuse | Link to thisIs it edible?
Reply | Report Abuse | Link to thishttp://blog.ted.com/2008/05/paul_stamets.php
Reply | Report Abuse | Link to thisHere's the link to Paul Stamets talk on Ted.
How is it possible for a fungus to grow to such a ginormous size. Almost unbelievable.
Reply | Report Abuse | Link to thisThat IS unbelievable. And here I thought that <a href="http://www.metalabsllc.com">foot fungus</a> was the only thing I had to worry about in Oregon; I guess I was wrong!
Reply | Report Abuse | Link to thisCan someone explain why 4 square miles equals 10 square kilometers if 4 miles equals roughly 6.4 km?
Reply | Report Abuse | Link to this4 square miles = 2 miles x 2 miles
Reply | Report Abuse | Link to this2 miles = 3.218 kilometers
4 square miles = 3.218 kilometers x 3.218 kilometers = 10.356 kilometers
Thank you, I realize now how I misinterpreted what that meant. Appreciated!
Reply | Report Abuse | Link to thisI grew up in Eastern Oregon, and one of my fondest memories was going in the spring on a family expedition led by my music teachers, the MacDonalds, to the woods in the Blue Mountains to find and feast on Oyster Mushrooms. We built a campfire and sauteed them in butter right in the woods. I remember they were usually about the size of pancakes. That was probably in the late nineteen forties or early fifties. They would be at the roots of trees, hidden under the forest mulch, and looked a little like sprawling sponges -- rather fibrous and really delicious.
Reply | Report Abuse | Link to this2mi x 2mi = 4mi^2
Reply | Report Abuse | Link to this2mi = 3.22km
so
3.22km x 3.22km = (roughly) 10km^2
Although, "worrying" might then be a desideratum .
Reply | Report Abuse | Link to this@KenFresno
Reply | Report Abuse | Link to this...if 4 miles equals 6.4 km then 2 miles equals 3.2 km.
...then 2x2 miles equals 4 sq mi as 3.2x3.2 equals 10.2 sq km.
...giving that nearly 4 sq mi equals 10 sq km.