A ‘second chance’: Morton Arboretum led discovery of oak tree thought to be extinct in Texas

Somewhere on the rugged, pathless hills of Big Bend National Park, under the sweltering Texas sun, a singular tree stands apart from the rest. At least for the people who know what they are looking for.

Its odds of survival are grim. The oak tree, standing stoically about 30 feet high, is scarred by fire and likely suffering from a serious fungal infection.

This was the scene a group of nine researchers, led by the Morton Arboretum and the United States Botanic Garden, came across when they found a specimen of Quercus tardifolia, a type of oak thought to be extinct since 2011, at Big Bend on May 25.

One of the researchers had called over Wesley Knapp, chief botanist at Virginia-based NatureServe. They faced a tall tree, sunlight filtering through its foliage.

“And (he) held up these leaves. And immediately I was like, ’Well, we haven’t seen this,’ ” Knapp recalled.

Three days in, their expedition had already encountered thousands of oaks, Knapp said. But nothing quite like this. Q. tardifolia is one of — if not the rarest — oak there is. And one of the ways to identify it is by its leaves, which look hairy.

“It was kind of one of those things where no one wanted to just jump up and down immediately,” Knapp said. “But then, as we started to look at the material and feel the thickness of the leaves, noticed the hair on the undersurface, we all kind of collectively realized that this is a dead ringer for Quercus tardifolia. And then excitement started to really grow.”

For the trip, researchers from across the country headed to the Lone Star State to see if they could locate the oak. Murphy Westwood, vice president of science and conservation at the Morton Arboretum, led the project alongside the United States Botanic Garden.

Westwood said the research trip to Big Bend was prompted by a 2017 study of threatened oaks in the United States, which cataloged 91 native oak species that are under the risk of extinction, and a 2019 report on a conservation gap analysis that identified 28 species of concern, coupled with the knowledge that Southwest Texas is a hotspot for oak diversity in the country.

Some of the leaves collected from the specimen on the discovery trip were sent to the Morton Arboretum for molecular analysis, Knapp said. So scientists will study the DNA composition of the oak and pinpoint whether Q. tardifolia is its own species or if it is a “weird hybrid,” as Westwood put it.

But besides excitement, the discovery of the tree also offers cause for concern: Its location makes it vulnerable to wildfires and droughts, which are more likely every year due to climate change, researchers said.

“This individual tree could be on the precipice of dying,” Knapp said.

The researchers said they don’t know the age of the tree because that would require a procedure to read the rings in its core, which could damage the already struggling oak. But its existence means that there may be other specimens of Q. tardifolia around.

“If we found one, there’s certainly a chance that we could find more, and we are going to go back and keep looking and we’re going to do the work to try to prevent this (tree) from disappearing,” Westwood said.

The National Park Service and the group are working to protect the oak from fires and the researchers will soon search for acorns to try to help the tree breed.

“So when we go back, now that we know that it’s there and we know that it’s struggling, a top, top priority for us now is to do things to mitigate the risk to that individual,” Westwood said.

That includes clearing the underbrush, which can act as fuel in case of a wildfire, so that the tree is better protected from a possible blaze.

Oak trees — one of which is the state tree of Illinois — carry out important ecosystem functions, Knapp and Westwood said. They are important sources of food and habitat for pollinators like butterflies and moths. In addition, they are a keystone species for other wildlife and plants, which means that the ecosystem would be very different or not exist without it.

“So, preserving oaks is preserving much more than just oaks — it’s preserving pollinators, wildlife and our forests,” Knapp explained.

Studying specimens such as this endangered oak, researchers said, is necessary to prevent other organisms from suffering the same fate.

According to Westwood, a discovery like this underscores that biodiversity exists beyond the Amazon rainforest and the jungles of Southeast Asia.

“We have really unique and really threatened plant species right here. In our own backyard, right here, in the States, we have them here in Chicago, we have them in Texas,” she said. “We have our own sort of natural heritage and biodiversity that we can be conserving.”

The rediscovered oak offers hope, too. In a world where bad news of climate change and biodiversity loss predominates in the main narrative, to Westwood, this discovery means a second chance.

“We thought we lost this oak, right? We thought we lost it, and we have found it. So we have this second chance and that, I think, is the good news,” Westwood said.

“We know we’re losing species to extinction all the time. Here is our opportunity. We have the technology, we have the knowledge, we have the resources to prevent another extinction and I think it is absolutely incumbent upon us to do that.”

adperez@chicagotribune.com