This hart is in the right place: One plant’s recovery story
By Meagan Racey
German botanist Frederick Pursh got his big break in 1807. The 33-year-old was hired with $60 in Philadelphia to catalog and illustrate plants from the Lewis and Clark Expedition.
But before Pursh began that endeavor — which would actually end with him running off to Europe with many of those specimens and publishing there — he was committed to a plant collection trip.
His journey — sometimes on foot, sometimes by carriage — included a discovery that publications would recount for centuries to come.
On July 20, 1807, in a valley west of Onondaga Lake, New York, Pursh found American hart’s-tongue fern (Asplenium scolopendrium var. americanum) tucked into the large limestone rocks. A resemblance to the European variety caught his eye.
“I thought the most of Asplenium scolopendrium — this fern which I don’t find mentioned by any one to grow in America I allways had a notion to be here; and indeed I was quit enjoyed to find my prejudice so well founded in truth [sic],” wrote Pursh in his journal.
The site was lost, then found, threatened by quarrying and timber harvest, and stressed by invasive species and weather patterns. It’s also been surveyed, researched extensively, boosted with captive-grown plants, and received the best care science can bestow upon it. Plus, it’s protected into the future as Split Rock Unique Area.
That may be the original American hart’s-tongue fern tale, but a recent review shares similar advances across much of the plant’s range — primarily a narrow band stretching from the Upper Peninsula of Michigan, through south-central Ontario and into Central New York. As a result, the U.S. Fish and Wildlife Service recommends the plant be removed from the federal threatened species list. If finalized, the decision would close a 31-year chapter in a story certain to continue.
Of harts and minds
Ferns have their roots far, far into the world’s past. They are among the earliest plants recorded, their existence stretching back about 400 million years. Roughly 70 species of ferns exist in New York alone.
While not showy like their flowering relatives, they have enjoyed a certain snob appeal. One 19th-century botanist insisted that “the beauty of form and texture of ferns requires a higher degree of mental perception and a more cultivated intellect for its proper appreciation.”
Don Leopold begs to disagree. “You don’t need to be a Ph.D. to appreciate” the American hart’s-tongue fern, said the distinguished professor and ecologist at the State University of New York in Syracuse. “The hart’s-tongue fern is really one of the most beautiful native plants you’d ever see.”
The American hart’s-tongue fern has a shiny, tropical look to its evergreen, strap-like fronds; at the furled stage the fronds bring to mind Fruit by the Foot candy, rather than the scroll of a fiddle. Long, tongue-shaped leaves inspired the name, referring to a deer’s tongue, specifically that of a red stag or “hart” in medieval times. The backside of the leaf bears cinnamon-colored sacs called sori.
The shade-loving fern most often grows in the crevices of calcium-rich limestone under mature maple forests. The New York state botanist in 1917 described the habitat there as “cool, densely shaded, mossy rock strewn gashes in the earth’s crust,” evidence of “the rugged forces of nature which have so deeply impressed their power upon the visible landscape.”
The fern has drawn fans like American photographer H. E. Ransier, who in 1926 wrote: “Richer than millionaires! Happier than Kings! Envied by multitudes! May be said of hobnobbers with Hart’s-tongue.”
Ransier was involved in one of the first attempts to save the fern. In 1924, operations were well underway to create a quarry in Jamesville, New York. The fern was not alone in its devotion to limestone. Three of its populations were in the path of explosives. It was one of a handful of quarries that would influence the plant’s future.
“Fern enthusiasts did their best to save what they could,” said John Wiley, the Service’s lead biologist for the species.
So they moved them.
Upwards of 700, maybe even 1,000, plants were replanted in nearby sites. Ransier even offered American Fern Society members “living specimens… at 25 cents and postage. Immediate application is imperative.”
Ransier and others shipped plants as far west as California, north to Maine and south to Missouri.
The fern enthusiasts’ hearts were in the right place, if not their science. “We wouldn’t advise that now,” said New York biologist Mike Serviss — the potential to spread invasive species and all that.
There’s little data about any of the shipped plants, according to Serviss. And records suggest the New York plantings did not survive.
The call for a hart transplant
Transplanting ferns took root again decades later.
By 1989, the Service was aware of just 16 populations of the American hart’s-tongue fern — nine in New York, four in Michigan, and a few distinct and separate populations in eastern Tennessee and northeast Alabama. Biologists reported the plant in six counties in Ontario, Canada, but knew only that healthy populations existed in two of the counties — and isolated ones in the others.
“It is threatened throughout most of its range by trampling, habitat alteration, or destruction by lumbering, residential development, and quarrying,” the Service wrote in the final decision to list the species. The 1993 recovery plan called for research, surveys, management, protection — and reestablished populations.
The SUNY College of Environmental Science and Forestry, namely Leopold and fellow professor Danilo Fernando, took up the challenge.
Leopold was already working on the fern. Fernando was a ready partner.
“I was curious about the level of genetic diversity of the species, as it tells us a lot about the plant’s reproductive strategy and evolutionary potential,” Fernando said.
In other words, when they found low genetic diversity, raising plants in captivity and using them to increase diversity seemed like a strategy worth pursuing. By intermixing genetically distinct individuals, “their future would be much brighter,” Fernando said.
With funding from the Service through the Great Lakes Restoration Initiative and federal endangered species grants, Leopold and Fernando spent several years developing and refining their methods.
“It actually required much more work than what I initially thought,” Fernando said.
The process bears no resemblance to growing standard garden vegetables from seeds.
“Sometimes you just look at them wrong and they die,” joked Serviss.
Backyard tomato-growers everywhere share the feeling.
Nonetheless, ferns need much more attention to get growing. Spores, the fern equivalent of seeds, are taken from parent plants and placed in soil-filled petri dishes in a temperature and light-controlled lab. While plants from different locations are not mixed, spores from different plants are mixed for diversity.
The spores grow into gametophytes, one of the two phases in this fern’s life. The gametophyte will ultimately appear as a small heart-shaped, leaf-like structure. It will release sperm and fertilize the egg. Fertilization can take 2–3 months.
The egg forms into a zygote. Within a month, it develops a root, stem and leaf. It’s now in the second phase of life — a sporophyte — and is recognizable as a fern. Scientists call the first growth a sporeling, the fern equivalent of seedling.
The sporelings are potted, kept for a period in the lab, and then acclimated to seasonal changes. It takes another 2–3 years before these plants can produce their own spores, and their fronds may only be a couple inches long at this point.
“It’s a patient person’s game,” said Serviss, who began work with Leopold and Fernando in 2014 as a student.
Their patience paid off in July 2015. The trio, aided by students and volunteers from the Friends of Recreation, Conservation and Environmental Stewardship (FORCES), planted their lab-reared ferns at three sites. That included Split Rock, the site of Pursh’s discovery more than two centuries earlier.
“Coming together and getting plants in the ground was a huge step,” Serviss said.
Nearly a century after the first known 1926 translocation, all signs pointed toward success. Well, 30 percent survival truly is success in this case.
“The next milestone was putting together data and figuring out some of the things that were really important,” Serviss said.
Those efforts are bearing fruit. Following a 2019 planting in Chittenango Falls State Park using ferns grown at SUNY-ESF, one out of every two transplanted ferns are now surviving, Serviss said.
Serviss now works for the new lead for the propagation program, the New York State Office of Parks, Recreation and Historic Preservation. With ongoing help from the Great Lakes Restoration Initiative, the program is transitioning to the NYS Parks’ Plant Materials Program greenhouses at Sonnenberg Gardens and Mansion State Historic Park. About 2,500 plants from New York stock are cared for there.
Following the hart
Botanists considered New York to be the stronghold for the species for many years. Discoveries from the predictable to the perplexing would reveal otherwise.
In 1989, the Michigan Natural Features Inventory recorded the fern in four populations in a single county. The nonprofit Michigan Nature Association had already acquired property to protect some of these plants, having been alerted to their existence in 1964. It’s since acquired more.
Biologists identified four more populations by 1993. By 2012, two more. Then, for the first time, they did a full count of plants at the two MNA sites. Turns out they are the largest populations in the U.S.
The state is now estimated to be home to thousands more plants than New York — more than half the plants in the country.
“To protect the ferns in our care, MNA is primarily concerned with maintaining the forest to the best of its ability in order to maintain the very specific microhabitat conditions required for this species to persist,” said Andy Bacon, the MNA conservation director. That includes ensuring adequate shade, addressing invasive species, and helping the forest maintain diversity to improve resiliency amid climate change.
Hiawatha National Forest in Michigan’s Upper Peninsula is home to nine American hart’s-tongue fern populations. The U.S. Forest Service has given forest stands containing the fern special treatment, ensuring routine monitoring and protection from activities that could negatively affect the populations.
Robert Leibermann recently became a botanist for Hiawatha, where a fern with a fancy name caught his fancy.
“I think it’s very enigmatic,” Leibermann said. “… My job as botanist will be to continue to stress the importance of it, and try to make sure it is protected.”
Canada perhaps marks the most significant advances in recording populations. The first comprehensive assessment — not completed until 2000 — uncovered more than 70 populations with several having thousands of plants. The number of populations jumped to 109 in 2016, and 112 in 2020.
Turns out Canada is home to more than 85 percent of the global American hart’s-tongue fern population.
The fern had yet one more secret. Laura Baumann of the National Park Service uncovered it. The biological science technician works nowhere near the known populations in eastern North America.
She’s in New Mexico.
In 2017, she was counting bats in basaltic lava flow caves in El Malpais National Monument. Using climbing gear, she dropped into a couple of caves they don’t regularly monitor. Seeing a body-sized crack between them, she checked it out.
“There were all these plants on the ground,” Baumann said. Plants where usually only moss occurs. “Seeing leafy vegetation in a cave feature like this was pretty wild.”
Two years after her cave adventure, Baumann reached out to experts to give her discovery a name. Initial assessments point to the American hart’s-tongue fern. In-depth genetic analyses will be underway soon.
“It’s been pretty validating because I don’t consider myself a botanist,” Baumann said. “… I’ve been really excited about how excited other people are getting about it.”
So how did the fern get to New Mexico? Probably not by Ransier’s shipments, Serviss said.
It’s possible the fern once had a much larger range during and following the last glacial age, but as the climate changed, the fern found proper habitat only in certain sinkholes, caves and steep-sloped basins, he said. Hence sites in Tennessee, Alabama and New Mexico.
Indeed, not long after its discovery, scientists recorded the plant in Mexico. Experts know little about the population in Parque Nacional Cumbres de Monterrey in northeast Mexico in Nuevo Leon, and aim to learn more.
The Service now reports 145 populations in the U.S. and Canada, and potentially more in Mexico. More than half of these populations have some sort of protection.
“The most important thing when it comes to most species’ conservation is making sure they’re protected within their habitat,” Serviss said “… It helps not only that species but it helps all those other plants and wildlife in the area.”
The Service’s next step is to work with partners to develop a monitoring plan for the species and to begin a peer and public-review process to propose delisting due to recovery, and then make a final decision.
In the latest review of the species, finalized in July 2020, the agency notes that “considerable efforts have been conducted” toward recovery. That includes confirmation of stable populations, a first-time estimate of the entire population north of Mexico and a comprehensive status assessment capturing the species’ genetics, ecology, life history and propagation methods. The agency predicts that the core populations around the Great Lakes will remain large and well-distributed for at least the next 30–50 years, even if a few populations elsewhere are lost.
“With $350,000 in federal funding the last ten years or so, at least five masters theses, several journal articles, a lot of work on understanding ecological and propagation, a dedicated group of stakeholders… you can get to recovery,” said Wiley, the Service’s lead biologist for the species.
But recovery isn’t the end.
Around 50 plants at Sonnenberg Gardens, grown at SUNY-ESF from spores of Alabama plants, await a drive to their new home in a cave entrance at a former fern site at the Service’s Wheeler National Wildlife Refuge in northern Alabama.
Tennessee would benefit from captive-reared plants, too. Serviss and colleagues were unable to find plants mature enough from which to collect spores, but just this spring they were able to bypass the spore reproduction process and culture them from tissue. They hope this could be a strategy for Tennessee’s population.
Clearly, more chapters lie ahead in the ongoing 200-year-old tale of the American hart’s-tongue fern.
The effort to conserve at-risk wildlife and recover listed species is led by the Service and state wildlife agencies in partnership with other government agencies, private landowners, conservation groups, tribes, businesses, utilities and others. It has drawn support for its use of incentives and flexibilities within the ESA to protect rare wildlife, reduce regulations and keep working lands working. Learn more at fws.gov/at-risk.