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.

    逛超市時，你看到的白色蘑菇大多小巧玲瓏，但在美國俄勒岡州的藍嶺上，蘑菇的一個“近親”的體積卻超乎想象：占地965公頃，相當于1665個標準足球場！

    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.

    這個學(xué)名為奧氏蜜環(huán)菌（Armillaria ostoyae）的巨型真菌是在1998年被發(fā)現(xiàn)的，它的出現(xiàn)刷新了世界最大生物的紀錄，而在此前，人們公認世界最大的生物是33.5米長、200噸重的藍鯨。按照生長速率估計，這個巨型蘑菇是年齡應(yīng)該為2400歲，但科學(xué)家猜測，它的實際年齡可能有8650歲——地球上年齡最大的生物之一。

    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.

    一個由森林學(xué)家組成的團隊在俄勒岡州東部統(tǒng)計致病真菌的數(shù)量時，意外發(fā)現(xiàn)了這個體積超大的“蘑菇”。他們采集了一些樣品，與實驗室培養(yǎng)的真菌比對，看它是否由多個相同的個體組成，并用DNA指紋技術(shù)分析它的遺傳性質(zhì)，確定組成它的每個成員的大小。

    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.

    奧氏蜜環(huán)菌是造成桑根朽病(armillaria root disease)的直接原因，美國個加拿大的很多松樹就是生了這種病，慢慢枯朽而死。一般說來，真菌會沿著樹根生長，伸出菌絲并分泌很多消化酶。但奧氏蜜環(huán)菌有獨特的生長方式：延伸菌根，連接食物源與菌體，然后迅速向外生長。

    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."

    優(yōu)勢基因的結(jié)合，再加上穩(wěn)定的環(huán)境，使得這種巨型真菌可以在幾千里保持活力。加拿大生化學(xué)家梅龍 史密斯（Myron Smith ）說：“奧氏蜜環(huán)菌確實是一種奇怪的真菌，總的來說，憑借強大的菌絲網(wǎng)絡(luò)，它可以長得無限大。”

    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.

    蜜環(huán)菌得名的原因是，它們具有黃色的圓蓋和帶有甜味的菌體。實際上，科學(xué)家首次發(fā)現(xiàn)巨型真菌實在1992年——一種學(xué)名為Armillaria bulbosa的真菌占地15公頃。

    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."

    梅龍 史密斯曾在多倫多大學(xué)攻讀博士學(xué)位，他和同事是在一個闊葉林里發(fā)現(xiàn)15公頃大的真菌的。史密斯回憶：“我們當初并不是為了發(fā)現(xiàn)什么奇異的東西，只是為了觀察不同的真菌，然后用分子生物學(xué)的方法鑒別不同種類的真菌。”

    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."

    后來，史密斯利用最新出現(xiàn)的生物技術(shù)，比對了多個真菌的基因后，他發(fā)現(xiàn)，闊葉林中的Armillaria bulbosa真菌竟有1500多歲，重量至少不下100噸！美國威斯康星大學(xué)的生物學(xué)家拉 克羅斯（La Crosse）說：“人們知道這些真菌很大，卻不知道它們?yōu)槭裁茨荛L這么大。在真菌學(xué)史上，rmillaria bulbosa絕對是最大的一種真菌，而且可能會永遠保持世界最大生物的紀錄。”

    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.

    但很快，科羅拉多大學(xué)的特里 肖（Terry Shaw）又在威斯康星的西南部發(fā)現(xiàn)了更大的真菌——一種奧氏蜜環(huán)菌，占地600公頃。2003年，又一位美國科學(xué)家發(fā)表報告稱，他發(fā)現(xiàn)了2384公頃大的真菌。

    Ironically, the discovery of such huge fungi specimens rekindled the debate of what constitutes an individual organism. "It's one set of genetically identical cells that are in communication with one another that have a sort of common purpose or at least can coordinate themselves to do something," Volk explains.

    這些超級真菌的出現(xiàn)，讓人們重新開始討論一位問題：是什么組成了這些巨無霸？美國科學(xué)家沃爾克說：“巨型生物都由相同遺傳性質(zhì)的細胞組成，它們可以相互交流，共同執(zhí)行一些復(fù)雜功能。”藍鯨、超級真菌、6615噸重的歐洲顫楊都符合沃爾克對超大型生物的定義。

    Both the giant blue whale and the humongous fungus fit comfortably within this definition. So does the 6,615-ton (six-million-kilogram) colony of a male quaking aspen tree and his clones that covers 107 acres (43 hectares) of a Utah mountainside.

    從這個角度來說，我們平常吃的蘑菇也是一種大型生物：一個農(nóng)場每年可以收獲幾十噸蘑菇，但這些長在塑料蓬中蘑菇，都具有相同遺傳性質(zhì)！

    In fact, humongous may be in the nature of things for a fungus. "We think that these things are not very rare," Volk says. "We think that they're in fact normal."

    沃兒克說：“實際上，對于真菌而言，體積巨大是一種很平常的事情。只是人類從未發(fā)現(xiàn)這一點。”