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Help Preserve and Protect Rare, Threatened, and Endangered Plant Species

in the C&O Canal National Historical Park


A Biodiversity Treasure in Peril

The C&O Canal National Historical Park (NHP) is beloved by millions for its natural beauty, rich recreational opportunities, and accessibility for over five million visitors. What is less well known is that it is one of the most biologically diverse national parks in the nation. Since its creation in 1971, over 1,500 plant species have been identified in the Park, including over 200 rare, threatened, or endangered (RTE) plants, some of which are globally rare and unique. But that number appears to be dwindling. Between 2008 and 2021, just over 100 previously identified RTE species were found along the C&O Canal. The remaining plants are likely now locally extinct. Invasive non-native plants, regional urbanization, and surging visitation have all taken their toll on the fragile habitats that make such diversity possible. With the addition of unfolding climate change, the National Park Service (NPS) is facing complex challenges to conserve this national biodiversity treasure. Its ability to meet these challenges, however, is severely impacted by capacity constraints resulting from ongoing shortfalls in the NPS operating budget.


A Unique National Park

Scour habitat along the Potomac River

Scour habitat along the Potomac River. Image courtesy of NPS.

The C&O Canal NHP runs 184.5 miles, traversing four physiographic provinces. From the Appalachian Mountains, through the Blue Ridge Mountains and the rolling farmland of the Piedmont, to its terminus on the Atlantic Coastal Plain in Georgetown, the C&O Canal NHP contains a rich mosaic of different habitats that host 68 distinct plant communities, 12 of which are globally unique. These habitats are the result of a variety of geological formations, most notably the Potomac Gorge and the shale barrens of the Appalachian range. Frequent flooding along the Potomac causes tree canopy gaps, scouring, and silt and seed deposition along the length of the river. Many northern and southern plant species overlap in the Park, with isolated populations of western species surviving where prairie habitat persists along the Potomac. Such diversity extends to fauna, which depend upon these varied ecological niches to thrive.

Along the Potomac Gorge, the geology and hydrology of the river flowing over Great Falls has created a biodiversity “hotspot” comprised of the most diverse flora located within an urban area on the entire East Coast. Upriver, the shale barrens of Allegany and Washington Counties, constitute a globally rare natural community where RTE plant and animal species are adapted to its harsh conditions. The steep slopes, constantly weathering shale, and continual undercutting of the Potomac limits soil development leading to the evolution of rare, endemic species found nowhere else in the world.

A Conservation Partnership with the C&O Canal Trust

Snow trillium, Trillium nivale

The only population of Snow trillium (Trillium nivale) in Maryland is found in the C&O Canal NHP. Image courtesy of NPS.

With planning underway for the much-needed rehabilitation of the Billy Goat Trail System near Great Falls, the NPS turned to the C&O Canal Trust in 2020 to request funding to support a youth botany fellowship program to survey RTE plants in and around the area. With 102 RTE species, the Potomac Gorge, where the trails are located, is considered a top biodiversity “hotspot,” and is also the area of the Park most imperiled by exceptionally high visitor numbers. The purpose of the survey was to collect data from known rare plant populations and identify other threatened species to ensure that work on the trail system is sensitive to fragile habitats and endangered plants. The NPS will use this information to identify and relocate at-risk plants or collect seed for their propagation. These efforts will allow the Park to ensure the continued survival of the plant species while providing sought-after outdoor recreational opportunities. As the C&O Canal NHP’s official philanthropic partner, the Trust was able to provide a grant of $64,757 to support this important work.

Over the spring and summer of 2021, the botany fellow located and identified 176 new and existing occurrences of RTE plants in the Great Falls area, and 331 RTE species occurrences Park-wide. Unfortunately, 91 species that had been previously known to exist in the Park before 2008 were unable to be located again.

Biodiversity Campaign to support Rare, Threatened, and Endangered Plants

The NPS is focused on facilitating the long-term conservation of RTE species throughout the C&O Canal NHP with a strategy that includes comprehensive identification, monitoring, habitat protection, seed collection, plant propagation, and establishing new populations of RTE species in unique habitat niches in the Park. For it to be successful, however, it will need the help of our canal community to supplement available NPS funding.

The C&O Canal Trust has raised $130,000 for the C&O Canal Biodiversity Campaign, thanks to our generous donors. Make a gift today, and help continue the work to protect this national biodiversity treasure.


For more information, please contact the development team at [email protected].



Top image by Chris Rief