“It was like when folks go searching for a lost child in the woods,” says Michael Eason, associate director of conservation and collections at San Antonio Botanical Garden. “Our team would spread out in a line, spaced about 30 metres apart, and comb through an area.”
Rather than a scene from a TV crime series, this search and rescue team of nine botanical researchers was scouring Big Bend national park in Texas this May looking for Quercus tardifolia, also known as the Chisos Mountains oak or lateleaf oak. The tree was first described in the 1930s, but the last living specimen was believed to have perished in 2011.
The search team, led by the Morton Arboretum and United States Botanic Garden, spent days inspecting each individual oak tree in the high Chisos, the previously known habitat of Quercus tardifolia.
On the third day, Eason found the oak in question, standing 30ft tall in Big Bend’s Boot canyon. “By this point, I’d looked at thousands of oaks,” Eason recalls. “But this one was visibly quite different than the surrounding trees for leaf colour, shape, leaf shine, and the way the leaves were hanging from the tree. Once I inspected the underside of a leaf and noticed the thick tomentum, I knew this was it. I was amazed and astonished at what I was seeing. As the team was radioed in and rallied, there was a sense of awe that we were quite possibly seeing the last remaining individual of this species.”
The oak was, however, in a poor condition, having suffered fire damage and showing signs of fungal infection.
“Since its discovery, there’s been a great deal of excitement and attention directed toward the species,” says Murphy Westwood, vice-president of science and conservation at the Morton arboretum. “The national park service is helping to monitor and protect the tree. Our local partners continue to scout for additional trees – we’re optimistic that new individuals will be discovered. Others will be returning to the site in the winter to collect samples that we can use to propagate the individual, for example through grafting or rooting cuttings.
“Our goal is to ensure the unique genetics of this individual aren’t lost. In the long term, we aim to propagate and grow this tree, and any others we discover, in botanic gardens as an insurance policy against extinction, and eventually to reintroduce the tree back to suitable habitats in the wild.”
Whether or not the oak can be brought back from the brink remains to be seen. But researchers also hope that by studying why the species is close to extinction, they may be able to protect others.
“We feel like we have a second chance at preventing the extinction of a species – something that doesn’t happen often in the biodiversity crisis we’re experiencing across the planet,” says Andrew Hipp, senior scientist in plant systematics and herbarium director at the Morton arboretum.
“This lone tree presents a unique opportunity to investigate questions about speciation, adaptation, hybridisation, conservation, and extinction,” he adds. “Understanding the diversity of oaks is particularly important because oaks are major contributors to the diversity and productivity of North American and Eurasian woody plant communities.”
It is also hoped that the rediscovery of such a rare tree in a popular, well-visited national park could help drive more research into the US’s existing plant life. And the results of the search in May may yet throw up another surprise.
“While we were looking for Q tardifolia, we were able to document additional locations of various species of orchids and other plants that are rare in the US, and we may have documented a new species for the US,” says Eason.
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