Treasures in the Sand: Protecting One of Michigan’s Rarest Plants

This is the first in a series examining rare, threatened and endangered species that have found their homes in the unique habitats of Northeast Michigan. 

On the remote shore of Negwegon State Park, where Lake Huron’s rugged coast gives way to long, narrow sand dunes, one of Michigan’s rarest plants is hanging on.

For most of its life, the Pitcher’s thistle is a wispy tangle of short, silver-green stems branching like antlers into slender leaves. Below ground, the plant will spend the better part of a decade sending a taproot 6 feet down, searching out nutrients as it stabilizes itself in shifting sands.

A mature Pitcher’s thistle flowers on the sandy shore of Big Charity Island, part of Michigan Islands National Wildlife Refuge in Saginaw Bay.

In its final summer, it puts on a show of pale pink blossoms, pollinates, makes seed and dies. This life cycle, evolved over millennia and specialized to a handful of places around lakes Huron and Michigan, is not compatible with the relatively recent arrival of invasive species, shoreline development and climate change.

“This plant is endemic to the northern Great Lakes,” said Samantha Nellis. “It’s an important aspect of these dune systems as food for pollinators and for its resiliency to storms. But it doesn’t exist anywhere else in the world and there’s nowhere else for it to go.”

DUNES UNDER DURESS

The Lake Huron shoreline, the longest of all the Great Lakes, supports unique and imperiled ecosystems with rare plant and animal species that exist nowhere else on Earth. The forested woodlands, dune and swale formations, karst geology and thousands of remote islands that all make up the Lake Huron Basin create the perfect backdrop for biodiversity. It’s these very habitats, however, that are threatened by invasive species and human development.

Huron Pines stewardship technician Logan Hawley looks over a young Pitcher’s thistle while pulling spotted knapweed from the dunes of Negwegon State Park, one of the plant’s last holdouts in the region.

Two particular invasive plants that have grave consequences for the Pitcher’s thistle and its habitat are phragmites and spotted knapweed. Phragmites, an aggressive grass that grows more than 10 feet tall in dense patches along the coast, absorbs wave action offshore and disrupts the formation of dune habitats. On shore, spotted knapweed chokes out native plants and emits a toxin into the soil that stunts the growth of nearby plants including Pitcher’s thistle.

Humans also pose a significant threat through increased shoreline development, beach grooming and recreational use which drastically minimize and disturb coastal dune and swale habitat. 

TO FIND, PROTECT & ENHANCE

Pitcher’s thistle is protected at the state and national level, and was officially listed as a federally threatened species in 1994 after decades of habitat destruction led to its decline. In recent years, Huron Pines has been increasingly focused on restoring, enhancing and protecting the Pitcher’s thistle’s critical coastal habitat through monitoring, research, invasive species removal and land protection efforts. 

Since 2014, Huron Pines has worked with conservation agencies, educators and community partners to give the 4th-grade students of Au Gres-Sims Schools a chance to support the future of the Pitcher’s thistle by conducting valuable field research on this rare plant.

Each year, Au Gres-Sims students get special permission from the U.S. Fish and Wildlife Service to visit Big Charity Island, part of Michigan Islands National Wildlife Refuge. Because of its protected status, the shoreline dunes provide relatively undisturbed habitat for Pitcher’s thistle. The biggest threat to the thistle’s growth is the phragmites that surround the island and can be found in abundance within Saginaw Bay. 

Thanks to funding and technical support provided by the U.S. Fish and Wildlife Service’s Coastal Program, Huron Pines visits the island annually to treat the invasive phragmites. Au Gres Sims students are tasked with recording data to track both the Pitcher’s thistle and the phragmites from year to year to see if the treatment is having the intended impact of supporting the Pitcher’s thistle growth. 

A windswept Pitcher’s thistle on the dune shore of Negwegon State Park

Additionally, Huron Pines staff and the Huron Invasive Species Network are working with Friends of Negwegon State Park to inventory Pitcher’s thistle and coordinate the removal of spotted knapweed in areas where the thistle has been found or could reestablish. The thistle monitoring and invasive species removal are funded in part through the National Fish and Wildlife Foundation, Sustain Our Great Lakes program and the Department of Natural Resources, Michigan Invasive Species Grant Program.

Sue Keller is cofounder of the Friends group and tagged along with the Huron Pines stewardship team on a trip to Negwegon in July to search out the Pitcher’s thistle.

“I had seen some before in 2013 when we were looking for the larva of Hine’s emerald dragonfly (another rare species),” Keller said. “We knew the habitat was right but we’ve never had a concerted effort looking at the dunes and treating the knapweed. Seeing them again was wonderful.”

As development pressure along the northern Lake Huron coast accelerates, it is more important than ever to prioritize land protection efforts that support natural coastline. To that end, Huron Pines is working with The Nature Conservancy and Friends of Thunder Bay National Marine Sanctuary to protect four miles of Lake Huron shoreline located in Alpena’s Thunder Bay. The parcel includes several rare plant and animal species including the Pitcher’s thistle. 

“The Pitcher’s thistle is a fascinating example of the threatened species located on the shores of Lake Huron that need special protection. It takes five to eight years before it flowers and it sets seed only once in its lifetime,” explained Katie Wolf, Community Outreach and Education Liaison with the Thunder Bay National Marine Sanctuary and Friends of the Thunder Bay National Marine Sanctuary. “Conservation areas and partnerships like North Point where rare and endangered plants are protected from shoreline development, ORVs, and heavy foot traffic, ensures that future generations will be able to appreciate and study such unique features of our Great Lakes ecosystem.”

A thistle hidden in the sandy dunes of Lake Huron may not be as charismatic as its mammalian counterparts but plants like the Pitcher’s thistle, dwarf lake iris and Houghton’s goldenrod represent a part of Michigan’s unique natural heritage and ecological diversity. They are among hundreds of threatened and endangered plants and animals across the state that are vulnerable to extinction if no effort is made to protect our most precious resources from development, human disruption and invasive species.


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