HSU's trailblazing mycologist Terry Henkel and students hack their way through South American jungles to uncover the secrets of tropical fungi
Arianne Aryanpur
Photos Courtesy of Terry Henkel, Jessie Uehling and Arthur Grupe

THE RAIN HAD just started to clear by the time Terry Henkel and his expedition crested the 6,000-foot summit of Mt. Ayanganna in Guyana, South America. They'd spent the past few days using machetes and climbing rope to traverse the country's dense bush, and were now surrounded by the surreal vegetation of the elfin cloud forest.

On the other side of the peak lay a tropical rainforest: a mushroom hunter's paradise. But as Henkel led his team in single file down the mountain, something caught his eye. Up ahead, illuminated in a beam of sunlight was a swarm of marabunta wasps—a species so aggressive they're nicknamed "horse killers."

"When you see a jaguar, you don't move, but stare it down," Henkel says. "But with the marabunta, you run as fast as you can in the other direction. Unfortunately, in this case we had to run straight down a steep, slippery mountain slope."

It may sound like something out of an episode of Survivor, but for Henkel—an HSU mycology professor and leading expert on tropical mushrooms—it's all in a day's work. For the past 20 years, Henkel has led students and colleagues on mushroom hunting expeditions to the Pakaraima Mountains of Guyana, one of the most biodiverse and poorly-studied regions of the world.

Over the course of his career, he's made significant contributions to the field of tropical biodiversity and rainforest ecology, and discovered many new species of fungi. Earlier this year, he was named HSU Scholar of the Year by President Rollin Richmond.

"His research has helped shape our understanding of tropical forests and led to many new lines of research inquiry on tropical forest mycology," writes Kabir Peay, a professor at Stanford University in a nomination letter for the award.

Adds Forestry Professor Steve Sillett: "Here's tropical mycology at its finest and most adventurous, exploring uncharted terrain in remote tropical rainforests and unearthing amazing secrets."

A Mushroom Hunter's Paradise

LOCATED IN NORTHEASTERN South America, Guyana is home to thousands of unique plants and animals. It remained virtually unexplored until the 1980s, when the Smithsonian Institution launched the Biological Diversity of the Guiana Shield Program, designed to document the region's diverse flora and fauna. Henkel worked on the program for two years before securing grants to fund his own expeditions through the National Geographic Society, the National Science Foundation, and other organizations.

Since becoming a faculty member in HSU's Department of Biological Sciences in 2002, Henkel's research has focused on ectomycorrhizae (ECM), a plant symbiosis that forms underground networks of "hyphae" around the roots of certain trees. ECMs are important because they have a unique capacity to help plants absorb vital nutrients from the soil. They're also particularly important in the study of forest ecology and biodiversity in the South American tropics. Says Henkel: "Much of my early research in Guyana involved unraveling the role of ECMs in promoting forest dominance by individual ECM tree species, a rare phenomenon in the tropics."

Henkel estimates that over 70 percent of the mushrooms his team collects are new to science. So far, they've formally named nearly 100 new species, but he says that hundreds more await the detailed study necessary to bring them to publication.

Among the most memorable? Boletellus piakaii, a species that Henkel named after his son, Piakai, who discovered the original specimen of the mushroom. There's also Amanita cyanopus, known colloquially as "Henkel's Blue Foot Amanita." The fungus' defining characteristics include a rich blue color and strong chlorine odor.

One of Henkel's recent discoveries was a new genus of truffle fungus. It is a wood-decaying fungus unique to Guyana that has a bulbous, wart-like exterior and gelatinized pink center, with spores apparently dispersed by termites. Henkel and his colleagues named it Guyanagaster necrorhiza, which roughly translates to "stomach fungus from Guyana that kills roots." "It's great fun picking these names," Henkel says.

One of the most rewarding parts of these endeavors is being on the biodiversity frontier, Henkel says. "Most of these tropical forests haven't been explored for fungi, so putting these species on the map is a big motivator. For me, it's a great way to combine science with hard core adventure."

From Field Collection to Publication

HENKEL HAS INVOLVED numerous students—both from HSU and Guyana—in his research. Several have gone on to prestigious Ph.D. programs, including at his alma mater Duke University. One of the most recent, Jessie Uehling ('12, Mycology), will begin her doctoral studies there this fall.

Uehling's master's thesis grew out of her four field expeditions to Guyana. She focused on identifying new species in the genus Clavulina. Her discovery of the new species Clavulina cerebriformis was the subject of a paper published in the scientific journal "Mycologia" in June, and was one of four such articles she published while at HSU.

Since 2002, Henkel has published more than 50 peer-reviewed articles, nearly half co-authored by HSU graduate or undergraduate students. To put this in perspective, it takes an average of one year to publish a taxonomy paper after collecting a new mushroom.

"The taxonomic process runs the gamut from field collection, description, and preservation, and getting out of the field with specimens intact," says Henkel. "Then, back in the lab, many hours of microscopic and DNA analysis, and comparisons with herbarium specimens from around the world—all this to figure out if you have a new species. If so, then drafting of the manuscript is the next step," he says. "I have several lifetimes of work residing in my herbarium cabinets."

Collecting the mushroom is just one step in a long process. After a day of collecting, Henkel and his team return to their rustic camp to sort the fungi into species. Each species is first given a number, then a detailed description in a field notebook. The collection is photographed, and a small amount of tissue is extracted for subsequent DNA analysis. The collection is then dried with silica gel dessicant, which leads to a perfectly preserved specimen for further laboratory study. "To accomplish this under the torrential downpour conditions of the Guyana rainy season is challenging, but we get it done," Henkel says.

Along with morphological analysis, identification of mushrooms involves obtaining DNA sequences from the fruiting bodies and, in some cases, the ectomycorrhizal roots themselves. DNA sequence data for new species is routinely added to GenBank, an online sequence database administered by the National Center for Biotechnology Information through the National Institutes of Health. One of Henkel's goals is to make that information available to researchers worldwide through his website, tropicalfungi.org. The site also contains information about what it's like to conduct research in Guyana.

'Engaging Wilderness on Its Own Terms'

OUTSIDE OF COLLECTING data and processing specimens, a lot of time is spent getting from one camp to another, Henkel says. That involves transporting heavy loads of provisions, hiking, paddling canoes and cutting trails through the forest. Since expeditions typically take place during the rainy season, very wet conditions prevail.

"I tell participants, this is a great opportunity for field research, but not if you're going to get homesick during sixweeks in the bush," Henkel says. "You have to be seasoned in the backcountry, have a high threshold for physical discomfort, and be ready to engage the wilderness on its own terms."

From stinging caterpillars to swarming wasps, the surprises are endless. "We've had floodwaters fill our camps, leaf cutting ants steal our rice, and baby sloths fall out of trees onto people in the depths of the forest," he says. "The list of the scary and sublime is long, but with time, you see it all."

Critical for success is having local guides. Over the years, Henkel has developed a close relationship with the Patamona Amerindians, the indigenous people of the central Pakaraima Mountains. In addition to navigating the obstacles of the bush, they serve as parataxonomists, helping to collect mushroom and plant specimens as well as setting up study plots and measuring and identify trees. Many have been working with him since the early '90s.

"The Patamona have inhabited the forests of the Pakaraimas for centuries, so whether it's surviving on wild forest foods or finding the best route through the jungle, they know an immense amount about how to live in this land," Henkel says. "We wouldn't get to first base without them."

In return, he shares his scientific knowledge with them. Henkel conducts biodiversity workshops in Guyana for community members, local students, and forest rangers. The goal, he says, is to help train a generation of Guyanese conservationists.

Conservation isn't a priority issue yet in Guyana since the country has remained isolated and undisturbed for many years. But Henkel thinks that will change.

"We're talking about one of the most intact, biologically diverse tropical regions in the world," Henkel says. "One day we'll need a core group of people who are educated in biodiversity, who can inform the planners and help the country establish and manage a system of parks and reserves."

He adds: "Its gratifying that we're able to study mushrooms, but also contribute to the larger picture of nature conservation in this unique part of the world."

Professor Terry Henkel presents at the HSU Biodiversity Conference 2012, on Saturday, Sept. 29. For more info, visit humboldt.edu/biodiversity

Fungi Videos

Find more of Henkel's tropical fungi videos at tropicalfungi.org

Mt. Ayanganna expedition, June 2012. Team members (front to back) Shawnee Gowan (HSU Botany), Jessie Uehling (MSc. ´12 Mycology), David Clark (UNC-Ashville, botanist), and Dan Thompson (BSc. ´12 Botany).

Working on specimens in the bush camp (left to right) Francino Edmond (Patamona), Cathie Aime (mycologist, Purdue University), Piakai Henkel, Gwen Williams (Ph.D. student, Duke University) BELOW: Henkel leads a workshop for Guyanese students.

TOP:Henkel holds up a Clavulina craterelloides, an unusual Guyana mushroom BOTTOM: Dugout canoes are a common mode of transportation in the bush.

The Fungi of South America's Guiana Shield

One of the most biodiverse and poorly studied regions of the world, the Pakaraima Mountains of Guyana are home to thousands of unique plant and animal species. Here are some of the mushrooms Henkel and his students have discovered there.

Guyanagaster genus

This new genus of wood-decaying truffle fungus has a bulbous, wart-like exterior and gelatinized pink center, with spores apparently dispersed by termites. Henkel and his colleagues named it Guyanagaster necrorhiza, which roughly translates to "stomach fungus from Guyana that kills roots."

Boletellus piakaii

Boletellus piakaii is a species that Henkel named after his son, Piakai, who discovered the original specimen in the forests of Guyana.

Amanita cyanopus

Known colloquially as "Henkel's Blue Foot Amanita," this fungus' defining characteristics include a rich blue color and strong chlorine odor.

Clavulina cerebriformis

Graduate student Jessie Uehling's (MSc. '12, Mycology) master's thesis focused on identifying new species in the genus Clavulina. Her discovery of the new species Clavulina cerebriformis was the subject of a paper published in the scientific journal "Mycologia" in June, and was one of four such articles she published while at HSU.

Photos Courtesy of tropicalfungi.org

After leaving Arcata, it takes Henkel and his US team up to two full weeks before they're picking mushrooms in the jungle of Guyana.
A sample travel itinerary:

  • Domestic Air Travel: Fly from Arcata to San Francisco, hop on a red eye flight to Houston.
  • International Air Travel: Catch another flight to Trinidad and Tobago; take another red eye flight to Georgetown, the capital of Guyana; clear immigration and customs.
  • Load equipment and passengers on a nine-seater Islander aircraft into the jungle.
  • Carry supplies for 1–10 days into the jungle.
  • Set up base camp.
  • Begin field research.