The Mushroom at the End of the World: On the Possibility of Life in Capitalist Ruins (32 page)

Cosmopolitan science is composed of patches—and is richer for it. Yet individuals and events sometimes make a difference. Like mushroom spores, they may germinate in unexpected places, reshaping patch geographies.

17

Flying Spores

All of this is, of course, speculation.

—Mycologist Jianping Xu, discussing matsutake evolution

L
ANDSCAPES AND LANDSCAPE KNOWLEDGE DEVELOP
in patches. Matsutake shiro (mycelial mats) model the process: Patches spread, mutate, merge, reject each other, and die back. The hard work—and the creative, productive play—of science, as well as emerging ecologies, happens in patches. But one might also sometimes wonder: What moves beyond them, making them? For matsutake, there are also flying spores.

Both in forests and in science, spores open our imaginations to another cosmopolitan topology. Spores take off toward unknown destinations, mate across types, and, at least occasionally, give rise to new organisms—a beginning for new kinds. Spores are hard to pin down; that is their grace. In thinking about landscapes, spores guide us to in-population
heterogeneity. In thinking about science, spores model open-ended communication and excess: the pleasures of speculation.

Why spores?

Koji Iwase first started me thinking about spores. We were having lunch in Kyoto with Shiho Satsuka and Michael Hathaway; the tape recorder wasn’t on. I was curious about why matsutake is so cosmopolitan: How did it spread around the northern hemisphere? Dr. Iwase is generous with foreigners and willing to guide them. So he mentioned that the stratosphere is full of fungal spores; at those high altitudes they blow around the earth. It’s not clear, he continued, how many of these spores survive to germinate in distant places. Ultraviolet radiation kills, and most spores are viable only for a short time, perhaps a few weeks. He didn’t know if a matsutake spore could survive to germinate on another continent. Even if it did, he explained, it would have to find another germinating spore; without fusing, it would die in a few days. Still, over the course of millions of years, one might imagine that spores could spread the species.
¹

There is something about the stratosphere that inspires airy dreams. Imagine, spores circling the globe! My thoughts took off with drifting spores, chasing my protagonist across eons, across continents. I took my questions to mycologists here and there around the world, chasing their thoughts, too, through the stratosphere. I found a cosmopolitan science of speculation about origins and the making of kinds across space and time. Unlike the discontinuous patches of applied forestry, the science of matsutake speciation is not patchlike. There are strong winds of international consensus about methods; the materials—mushroom samples and DNA sequences—circulate across borders. Individuals and sometimes labs develop stories, bits of expertise, and even biases. But there are no schools, no patches. All this work is off the clock: no one gives out grants to study the eon-crossing travels of a mushroom. Scientists turn to these questions out of love—and because the methods and materials are there. Perhaps one day the combined results and speculations will lead us, like spores, to something new, they reason. For now, it is just the pleasure of thinking: the spore-filled airy stratosphere of the mind.

What are these materials and methods that circulate?

Henning Knudsen showed me the University of Copenhagen Botanical Garden’s fungal collection, of which he is curator.
²
Type specimens
are stored here: drawers and drawers of folded envelopes, each guarding a dried fungus. When a new species is named, the namer sends a sample to the herbarium, and those specimens become the “type” for that species. Researchers from around the world can ask to see the type; the herbarium sends the original material. The herbarium system emerged with the northern European passion for identifying plants, which also resulted in Latin binomial names. It was a feature of European conquest; it also created the basis for transnational communication through the circulation of specimens. Researchers around the world know species through type specimens collected in herbaria.

Dr. Knudsen does not think matsutake spread through spores in the stratosphere; it’s just too improbable that they would find mates. Instead, their distribution followed the forests: they spread together with the trees. This took a long time, but across the northern half of the earth, many species spread—ever so slowly—together. Some, such as
Boletus edulis
, may have spread across the top, from Alaska to Siberia. But the homogeneity of northern species is overstated. Many species that used to be seen as uniformly found across the global north turn out to be different species, he said.
³

The rejection of uniform cosmopolitan species draws not from the circulation of herbarium samples but from a revolutionary new technology, DNA sequencing, which offers a new way to define “species.” Mycologists examine particular DNA sequences—e.g., the internal transcribed spacer (ITS) region—that tend to be conserved within species but show variations across them. Jean-Marc Moncalvo, Dr. Knudsen’s counterpart at the Royal Ontario Museum in Toronto, explained that more than a 5 percent divergence in the ITS sequence indicates a new species.
⁴
DNA sequencing does not reject the materials and methods of herbaria; most comparisons across species use herbarium samples. But there is a new material here in circulation: the DNA sequences themselves. Databases have made it possible for scientists around the world to consult DNA sequenced by others. The simple precision of DNA sequencing has taken the scientific world by storm: there are no alternatives. It seems so powerful that scientists keep making up questions based on the availability of this answer.

Of course, there are still pockets of difference. Dr. Moncalvo explained that, as recently as the 1980s, Chinese mycologists had trouble
communicating freely with Europeans and North Americans. One Chinese mycologist sent him samples of fungi hidden between the pages of reprints. As a result of isolation, he said, Chinese taxonomies are strange. Internationally, there are no rules for naming a genus (the first name in a Latin binomial), so Chinese taxonomers have added “China” to genus names, assembling
Sinoboletus
instead of
Boletus
, and confusing foreign counterparts. Furthermore, they recognize species indiscriminately. They claim to have twenty-one species of oyster mushrooms in Yunnan, but there are only fourteen species recognized in the world. Tiny morphological differences are given too much attention. But this is changing now, he said, as young scientists with international training take over.

What do these materials and methods tell us about “kinds”?

Species has always been a slippery concept, and DNA sequencing—despite its precision—has not made it easier to handle. Classically, species boundaries were defined by the inability of individuals on each side to mate and produce fertile offspring. That’s easy enough to figure for horses and donkeys. (They mate but do not produce fertile offspring.) But what about fungi? Dr. Moncalvo walks me through what it would take to find out if two different fungal strains were species according to this definition. You would need to germinate one single spore of each in culture, get those spores to mate, somehow force them to produce a mushroom, then get its spores to mate and produce mushrooms. For a fungus such as matsutake, for which no one has succeeded in producing a single mushroom in culture, and whose spores don’t even germinate if alone, such experiments are hardly worth conceiving. Besides, Dr. Moncalvo added, imagine the hapless graduate student who devoted a dissertation to finding a species boundary of even the easiest-to-handle mushroom. Where would he or she get a job?

All this matters in getting to know matsutake across its diasporic locations. Twenty years ago, there were many, many species of matsutake scattered around the northern hemisphere, with more emerging constantly as scientists found them. Now there are just a few—and growing fewer. This is not because of extinction. DNA sequencing in the ITS region has allowed scientists to argue that most of those kinds of matsutake are really just one kind:
Tricholoma matsutake. T. matsutake
now appears to spread across most of the northern hemisphere, not just across Eurasia but into North and Central America. Only
Tricholoma
magnivelare
, the matsutake of the North American Pacific Northwest, is continuing to stand clearly as a separate species, and even it is very close, in its DNA signature, to
T. matsutake
.
⁵

The precision of DNA sequencing, which allows such determinations, also undermines confidence in the species as the basic category for understanding kinds. I first met Kazuo Suzuki, now president of Japan’s Forestry and Forest Products Research Institute, when new results were coming in about the identity of China’s oak-loving matsutake, at that time called
Tricholoma zangii
.
⁶
In Japan, matsutake are associated with pines; only false matsutake are found with broadleafs. The association between matsutake and conifers seemed part of its species definition. DNA studies showing the close relation between China’s oak-loving matsutake and Japan’s exclusively pine-loving ones caught researchers by surprise. Dr. Suzuki brought his younger colleague from Tokyo University, Dr. Matsushita, to our meeting to tell me the news himself: His examination of the ITS sequence had shown no species difference between oak and pine lovers.
⁷
But Dr. Suzuki, who had worked with matsutake for many years, did not accept this finding as the whole story. “It depends on what question you ask,” he explained. He told me about Armillaria root rot, a complex of species in which clear species boundaries may not be relevant. Armillaria root rot spreads across whole forests, stimulating boasts of “the largest organism in the world.” Differentiating “individuals” becomes difficult, as these individuals contain many genetic signatures, helping the fungus adapt to new environmental situations.
⁸
Species are open-ended when even individuals are so molten, so long-lived, and so unwilling to draw lines of reproductive isolation. “Armillaria root rot is fifty species in one species,” he said; “it depends on what you are dividing species for.”

I remember the discussion vividly: I was at the edge of my seat. Dr. Suzuki was treating species in the way cultural anthropologists treat their units: as frames that must be continually questioned to retain their use. The kinds we know, he implied, develop at that fragile junction between knowledge-making and the world. Kinds are always in process because we study them in new ways. This makes them no less real, even as they seem more fluid and beckoning of questions
.

Ignatio Chapela, a forest pathologist at the University of California, Berkeley, was even more adamant that the idea of “species” limits the
stories we can tell about kinds. “This binomial system of naming things is kind of quaint, but it is a complete artifact,” he told me. “You define things with two words and they become an archetypal species. In fungi, we have no idea what a species is. No idea…. A species is a group of organisms that potentially can exchange genetic material, have sex. That applies to organisms that reproduce sexually. So already in plants, where out of a clone you can have change as time goes by, you have problems with species…. You move out of vertebrates to the cnidarians, corals, and worms, and the exchange of DNA, and the way groups are made, are very different from us…. You go to fungi or bacteria, and the systems are completely different—completely crazy by our standards. A long-lived clone can all of a sudden go sexual: you can have hybridization in which whole big chunks of chromosomes are brought in; you have polyploidization or duplication of chromosomes, where a completely new thing comes out; you have symbiotization, the capture of, say, a bacterium that allows you to either use the whole bacterium as part of yourself or use parts of that bacterium’s DNA for your own genome. You’ve become something entirely different. Where do you break down the species?
⁹
”

To compare different kinds of matsutake, Dr. Chapela used herbarium specimens as well as fresh samples and sequenced ITS-region DNA. But he refused to imagine his results as fixed species. “You start getting these groupings that you can only name relative to each other. You can’t call them a species…. In the old taxonomic approach you say, ‘this is my ideal’—it’s completely Platonic—and everything is going to compare as a missed approximation to that ideal. Nobody will be the same as this, but you compare and see how close they are to this ideal…. If it becomes too different—by whatever measure, and the measures are completely arbitrary—you say, ‘oh this must be a different species.’” To avoid a false “scientific cover,” he speaks of “matsutakes” as all the varied kinds that enter the Japanese trade. His study did, however, find distinct genetic groupings by region. That means, he said, that genetic materials are not freely exchanged across those regions. “If you see good patterning, if you see good separation, that tells you that there is not much exchange between these groups.” These data show that cross-regional exchange of spores is unlikely on a regular basis.