18 minute read
Special Feature
Following the Hart: The 200 Year-Old Story of the American Hart’s-Tongue Fern
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.
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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 always 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 captivegrown 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 19thcentury 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’stongue 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.
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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.” Following the hart
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.
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.
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 Andrew 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’stongue 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.
The young furled fronds of the American hart’s-tongue fern bring to mind Fruit by the Foot candy, rather than the scroll of a fiddle. Photo courtesy New York State Office of Parks, Recreation and Historic Preservation (OPRHP)
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.
Reprinted with permission from a blog originally published by U.S. Fish and Wildlfe Service North Atlantic-Appalachian Region.
Where Rivers and Forests Meet
Michigan’s floodplain forests are rapidly disappearing. That spells trouble for the rare, threatened, and endangered species that have evolved to exploit the natural rhythms of springtime floods where rivers and forests meet. Climate change is expected to only make matters worse with heavier rains and more extreme flooding events.
In southern Lower Michigan, the populated landscapes of farms, homes, and towns create predictable, right-angle patterns of human settlement when viewed from above. But winding across and through those straight line grids of roads, crops, and developed blocks, sinuous corridors trace the paths of streams and rivers. A kayak or canoe trip down one of those rivers, with trees on either side, can feel a million miles away from the human altered surroundings that may lie mere yards beyond the forested riverbanks. These corridors often harbor something really important, a dynamic natural community called floodplain forests. As defined by the Michigan Natural Features Inventory (MNFI), floodplain forests are deciduous or deciduous-conifer forests found in the bottomlands along low-lying areas adjacent to larger streams and rivers. Their dynamism comes from the streams themselves - periodic flooding, scouring, erosion and sediment deposition follow the rise and fall of water levels, creating diverse microhabitats that are used by a wide variety of wildlife. Land Plus Water = Diversity Land meets water in a floodplain forest. When that stream or river tops its banks, it reshapes the bottom lands with tree falls, migrating river channels, new sediment deposits or erosional scour. These actions create fluvial landforms such as natural levees, backswamps, oxbow ponds, and terraces - all associated with a particular type of vegetation.
“These forests are “The species richness in the floodplain forests often very important found in places like MNA’s McCulley-Bastian Nature Sanctuary along the River Raisin in stopover or even Lenawee County is a special conservation focus,” says Rachel Maranto, MNA’s Stewardship nesting sites for Coordinator. “Several rare plants species are declining neotropical found here, and nesting prothonotary warblers - a neotropical migratory bird of state special migratory birds.” concern - have been spotted. And I especially love that you can often find really big trees in a floodplain forest, those that have been spared
Rachel Maranto, MNA from logging that occurred to make room for nearby agriculture or development.” Stewardship Coordinator
Floodplain forests are found adjacent to third order or larger streams and rivers throughout Michigan, but more extensively in the Lower Peninsula and with greater species richness in southern lower Michigan, according to MNFI. The rivers themselves tend to follow meltwater or outwash glacial channels, and were important to Indigenous people for settlement, trade and travel.
Key Concept
Ordering Streams and Rivers
Floodplain forests are defined as bottomlands adjacent to streams and rivers of third order or higher. But what is an order? Stream order is used to classify the size of the water body. First order streams are typically the smaller, outermost tributaries of a river system. Two first order streams can merge to become a second order stream and two second order streams flow into each other to become a third order stream as the tributaries grow the river’s size and current strength. Typically, first through third order streams are the brooks and creeks in the upper watershed or headwaters of a river system. Medium sized streams are third through sixth order, and very large rivers constitute six through 12th-order rivers - think Mississippi at 10th order and the Amazon as 12th. (Source: Stream Order: A Classification of the Rank of Streams and Rivers)
Rich floodplain forest biodiversity can be found in other MNA Nature Sanctuaries, including habitat for both common and rare species. For
example, one sanctuary includes an active Great blue heron rookery along with documentation of three state-listed neotropical migratory songbirds during nesting season - Lousiana waterthrush, Cerulean warbler, and yellow-throated warbler. In another, state endangered copperbelly watersnakes are found.
“These forests are often very important stopover or even nesting sites for declining neotropical migratory birds,” says Maranto, “Often they are the last forested bastion in a lot of agriculture dominated landscapes and are therefore valuable for a variety of plants and animals.”
Since Indiana bats (see Species Spotlight, p. 13) are found within a relatively short distance from McCulley Bastion, Maranto adds, there is a good chance they may be found at the sanctuary as well.
And although species diversity may be richer in southern Michigan, floodplain forests can be found in northern Michigan, including the Fred and Ethel Walker Memorial Nature Sanctuary along the Manistique River in the Upper Peninsula’s Schoolcraft County. Here, these forests are also important for neo-tropical migrating birds such as the black-throated green warbler, scarlet tanager, and ovenbird.
On the west side of the state, the floodplain forest community along the Coldwater River at the Dolan Nature Sanctuary in Kent County contains a large population of state endangered Virginia bluebells. “It is a spectacular site when the bluebells bloom in the spring,” says Robb Johnston, West Michigan Regional Stewardship Organizer for MNA. “They are a rare treasure, a fleeting springtime gift, drawing photographers and nature lovers alike to experience the vivid blue carpeted forest floor.” Johnston also celebrates the rich diversity of other spring ephemerals that share time and space with the bluebells to complete Dolan’s vernal palette: spring beauty, toothwort, wild leek, trout lily, and golden ragwort to name just a few. “The trees grow to giants and tip ups abound, lending a wild, primeval character to the lush riot of green on the forest floor,” he adds, “And Dolan rises further yet in my estimation due to its trails, allowing visitors easy access to the beauty and stillness of the floodplain forest. “
True to its name, the Coldwater River is a cold water trout stream with noted mayfly hatches, a prime trout food. The floodplain forest at Dolan helps protect that fishery as trees along the banks shade the river to moderate and cool temperatures in summer months.
A Priority for Wildlife
Hatching insects also mean more food for birds, especially early in the spring as migratory songbirds move through the state. Because of the importance to birds and other wildlife, including a number of animal Species of Greatest Conservation Need, floodplain forests are one of eight priority habitats named in Michigan’s congressionally mandated Wildlife Action Plan (WAP), which addresses conservation strategies for Michigan’s rarest wildlife.
Focal species in the WAP include the state threatened Cerulean warbler, a migratory songbird that nests and feeds high in forest treetops, preferring mature, bottomland forests
Cardinal flower, lobelia cardinalis, are a striking contrast to the heavily green forest floor. Known for attracting hummingbirds, the plant grows well in very wet soil. Photo by Robb Johnston. over upland forests. The federally and state endangered Indiana bat also finds a home in floodplain forests, as does the federally threatened and state endangered copperbelly watersnake, the latter with occurrences only in a few southern Michigan counties.
Threats to these impressive habitats are an all too familiar list - invasive plants and animals, hydrological modifications (levees, impoundments, channelization, dams), including those brought by climate change, habitat loss due to industrial, residential and agricultural fragmentation, and incompatible timber management. For those reasons, floodplain forests are both globally and state ranked as vulnerable.
Needed conservation actions include protecting existing floodplain forests such as those found at McCulley-Bastian, Dolan, and other MNA Nature Sanctuaries. But protecting upland buffers and adjacent wetlands is another important strategy, according to the WAP, as is managing invasive species, reforestation, education for landowners, and even assessing the intactness of floodplain forests to better determine their distribution and health status.
The state WAP also lists actions needed for the focal species, such as protecting known summer roosting locations of the Indiana bat and acquiring more data on the elusive cerulean warbler.
Sanctuary County
1. Dolan Nature Sanctuary Kent
2. Dowagiac Woods Nature Sanctuary Cass
3. Joan Rodman Memorial Plant Preserve Washtenaw
4. McCulley-Bastian Nature Sanctuary Lenawee
5. Thornapple Lake Nature Sanctuary Barry
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State Wildlife Action Plan priority areas for floodplain forest conservation (in light green) are spread through much of southern lower Michigan. Many of MNA’s Nature Sanctuaries 2 MNFI herpetologist Yu Man Lee holds a spotted salamander while monitoring a vernal pool at Pierce Cedar Creek Institute. Photo by Fauna Creative. exist within this area (dark green dots) and a few even contain this special habitat type (dark green squares)!
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- Dr. Georgia Peterson, Natural Resources Extension Specialist
Wildflowers carpet the forest floor along the Dowagiac River at Dowagiac Woods Nature Sanctuary. Photo by Kurt Jung.
A Green Fringe of Benefits
For sometimes being no more than a narrow, green edge along a river, the magnitude of floodplain forest benefits belie their seemingly limited size. Besides important habitat, they provide organic matter as sources of energy for aquatic organisms, woody debris for aquatic habitats, and store floodwaters. In the reverse, when water flows across the land to a river, the floodplain forest serves as a buffer, absorbing both the quantity and the energy of that flow while filtering pollutants. Hence, the floodplain forest at McCulley-Bastian, for example, helps to protect the water quality of the River Raisin and Lake Erie, which is threatened by extensive development of land for agriculture in the region and the intensive nutrient inputs through fertilizer and sedimentation that result.
MNA’s contributions to protecting floodplain forests extend beyond land protection. The Nature Sanctuaries are often sites for scientific research, conducted by academics and community scientists alike, as well as place-based education and stewardship for those who visit. Exploring a floodplain forest at an MNA Nature Sanctuary is sure to open up new worlds and understanding of a fascinating natural community. experience - a nature immersion in a quiet, twisty corridor, flanked by the cool shade of those forests in the floodplains, shielded from the straight lines of civilization.
Where to Visit Floodplain Forests
Several MNA sanctuaries in Lower Michigan provide great opportunities to explore floodplain forests including:
• McCulley-Bastian Nature Sanctuary, Lenawee County • Joan Rodman Memorial Plant Preserve, Washtenaw County • Dowagiac Woods Nature Sanctuary, Cass County • Thornapple Lake Nature Sanctuary, Barry County (best viewed by canoe or kayak from a nearby public boat launch, see pg. 14) • Dolan Nature Sanctuary, Kent County
Floodplain forests can also be found in many riverside public parks as these areas were either avoided by development because of their propensity to flood or because communities intentionally dedicated sections of river corridors as parkland and open space to assist with flood control. Great examples of floodplain forests can be found at Eliza Howell Park and Rouge Park along the Rouge River in the City of Detroit.
