Where Do You Hide a 100-Foot-Tall Tree?

Photo Credit: William Farfan-Rios

By Vincent Gabrielle
BU News Service

In the clouds 

Sometimes new species are just waiting to be noticed. That’s the case with Incadendron, a new species (and genus) of tree discovered in the Andean cloud forests. It’s one thing to discover a new species, it’s another to discover a genus. It’s basically equivalent to discovering oaks or maples.

The east Andean cloud forest forms a thin band thousands of miles long between the Amazon rainforest and the highland puna grasslands. The dramatic landscape is almost perpetually shrouded in mist and is far colder than the Amazon below. It teems with biodiversity. A full third of Peru’s mammal, frog and bird species live here and nowhere else.

Growing to over a hundred feet tall and two feet in diameter,  Incadendron loom large in the mist, hosting fuzzy lichens, woolly monkeys and the bright-orange Peruvian national bird, “the-cock-of-the-rock.” Yet despite  the tree’s prevalence in the landscape it took ten years and two scientists working 35,000 miles apart to notice it.

“For us plant geeks, it’s particularly exciting,” said Martin Quigley, executive director of the UC Santa Cruz Arboretum. New plant genera come up infrequently and randomly. “People could have been walking past this thing for years and never realized what it was.”

That seems to be the case. Kenneth Wurdack, one of the Incadendron’s discoverers, was aware of the tree for years. In 2003, Wurdack saw something funny among the preserved leaves and flowers in the Smithsonian plant collection. Some of the flowers displayed traits that matched two or more other genera. The large, woody unpalatable fruits were particularly strange. Wurdack suspected something was wrong with how they were classified but he didn’t have enough samples to make a conclusive finding.

He “shelved it because I didn’t have enough to go on,” Wurdack said. Years later, William Farfan-Rios, an ecology graduate student at Wake Forest University, reached out to Dr. Wurdack.

“I had been going through [different botanical] collections and found Ken Wurdack’s name and email on the website,”Farfan-Rios explained. “I had also asked [botanists] about specialists in this plant family.”

Farfan-Rios was finding trees in the Euphorbia family that didn’t fit into any genera while hiking, plotting and surveying the remote cloud forests. After collecting photographic samples of the tree and collecting life-history data, he wrote up a rough description and sent it to Wurdack. When Wurdack responded, it was more than he had hoped for.

“He told me, William, I agree with you that it’s probably a new species. But it’s also probably a new genus,'” Farfan-Rios said.

Incadendron Tree Manu National Park — Photo Credit: William Farfan-Rios

The biodiverse cloud forest is tempting to biologists to study but remains largely unexplored. That’s because it is geographically isolated. Few roads extend into it. Air and river travel are impossible. Until 1998, it was too dangerous to explore the area due to a longstanding border war between Ecuador and Peru. From 1941 to 1995, the two countries fought sporadically over the headwaters of the Maranon River. Hostilities ended in 1998 with the passage of the Brasilia Presidential Act, formally solidifying the border.

Even with the end of the fighting and the opening of the highlands, the remoteness of the region still made it difficult to explore.

“The Andes is super under-collected,” Farfan-Rios said. “The first collection was only 14 years ago.”  

The name of the new genus, Incadendron or “tree of the Inca,” honors the history of the Incas who lived in the region where it’s found. Historically, the Inca or other lowland peoples may have hunted or foraged in the cloud forest. The Incan highway, Trocha Unión, passes by many of these trees on its journey down to the valley floor. Villages that speak Quechua, the Incan language, still live in the highland regions of the park.

Slave raids conducted by the rubber industry 100 years ago drove many local people deep into the rain-forested valleys. The ancestors of these people are thought to be the “no contact” tribes of Manu National Park. The strict isolation from outsiders, linguistic drift and new environment make investigating the historical ethnobotany of the area very difficult.

For these reasons, Quigley commented, “People have discovered, forgotten, and rediscovered, plants and their uses throughout history.”

To prove Incandendron was a new genus, Farfan-Rios provided Wurdack with additional specimens beyond what was available in the Smithsonian collections and detailed ecological field notes. Gathering the flowers was of particular importance. Without compatible flowers, flowering plants cannot reproduce.

In addition to the physical differences, the scientific duo needed to confirm that the tree was genetically distinct enough to be a new genus. It was an exciting find for both of them. Wurdack said something like this would only come up a few times in his career.

It’s not just the rarity of such finds that makes them so important. The hyper-diverse cloud forest is at serious risk of disappearing, just as scientists are beginning to study it. The cloud forest is being pinched between an encroaching jungle and inhospitable tundra of the Andes.

The plants that compose the forest are highly temperature sensitive. They can only exist in the narrow, moist band above the Amazon and below the high-altitude semi-arid permafrost grassland. As the temperature rises, the Amazon climbs higher and higher, pushing the cloud forest upward.

Ecological surveys indicate that in some places, the cloud forest has retreated upwards by 200 meters. But those plants can’t climb forever. The grasslands above are a hard border. It’s too cold, windswept and dry for trees.

But it’s not all doom and gloom. The finding shows us that we still have things left to discover.

Quigley of UC Santa Cruz emphasized that this find opened an entire new window into plant evolution. The cloud forest is so different from other nearby environments that the plants have had to change in drastic ways to survive. We still have lots to discover among these giant trees with forgotten names.

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