More Plants Are Going Extinct Than We Previously Thought

Researchers found what they describe as a 'more dire situation.'

Franklin Tree, (Franklinia alatamaha), Possibly Extinct (GX) in the Wild. —a cultivated example of this species as no known wild individuals exist.
A cultivated example of Franklin tree, (Franklinia alatamaha) which is possibly extinct in the wild.

 John Bartram Association / Bartram's Garden

A new study finds that 65 plant species have gone extinct in the continental United States and Canada since European settlement. That's nearly twice as many species that researchers had previously estimated or any study had ever documented.

The study was published in the journal Conservation Biology by a team of 16 conservation and biology researchers from across the U.S.

Although recent studies suggest that nearly 600 plants have gone extinct around the world including 38 plants species in 16 U.S. states, instead researchers found what they describe as "a more dire situation." Their results document 65 extinct species in 31 states, the District of Columbia, and in Ontario, Canada, suggesting more extinctions over a larger area than previously estimated.

It's likely, they say, that the documented extinctions highly underestimate the actual number of plant species that are lost.

The states with the most extinctions are California (19), Texas (nine), then Florida, and New Mexico with four each. Canada had just one plant extinction.

"There were a number of interesting discoveries. I was surprised at the geographic distribution of extinction events being southwestern. We were very surprised at the number of plants that were apparently known from a single site (i.e. extremely narrow geographic distribution)," lead author, ecologist and botanist Wesley Knapp of the North Carolina Natural Heritage Program of the North Carolina Department of Natural and Cultural Resources, told Treehugger.

"I think the largest surprise is the fact that up to seven plants are extinct in the wild (i.e. only known from botanical gardens), and some of these species weren’t known to be extinct in the wild before this study. Frankly, this is shocking."

Some of the species that are now extinct in the wild exist only in botanical gardens and the facilities that had them didn't realize they had the last living plants in the world, Knapp said.

Interesting Geographical Issues

Some of the geographic locations for the extinctions are also surprising, Knapp said.

"The fact that New England has more extinction events than Florida is counterintuitive and highlights the fact that untold number of species likely went extinct before they were ever found. New England is a special area, but botanically it is not near as diverse as Florida, which is located in a global biodiversity hot spot with hundreds of endemic plant species."

The cause of the extinction is difficult to determine, the researchers wrote. Knapp said the results are important and hopes that researchers can learn from them.

"One point I hope people take from the work is that the scientific community needs to work more collaboratively. Groups that know where the rarest plants are found, like the North Carolina Natural Heritage Program, need to work closely with seed banks and conservation gardens to help conserve genetic material (i.e. ex situ conservation)," Knapp said.

"We should start by focusing on global single site endemics. We also need to closely look at our ‘protected lands’ to make sure we’re capturing the full array of biodiversity. Lastly, many conservation groups work on larger landscape level initiatives or focal areas. This is wonderful for ecosystem function, however the importance of small site protection for biodiversity conservation is imperative to protect extinction."

When Knapp was an undergraduate student, he was tasked with surveying two counties in Maryland, looking for rare plant species. The plant Nuttall’s Micranthemum (Micranthemum micranthemoides) captured his imagination, he said, as this is the only plant believed to be extinct in Maryland.

"I did not realize extinct plants were found in places like Maryland, assuming they were only in far off species places like the Amazon. Over the years I’d talk to other botanists about what plants were extinct in their states. I found that most people didn’t know much about the plants that were presumed extinct where they were working, so I started maintaining a list of the extinct species," he said. "To my surprise, the work had not been done and everyone was on board that it was an important topic to investigate."