Stevens uses flags to measure the size of a pasture heliotrope (Heliotropium tenellum) population, also recording how many plants are reproducing.

“It’s always exciting when you find the plant you came to see. You’re hoping it’s still there,” Stevens said. “I was surprised at just how much of a personal investment I’ve taken. When a plant population is doing well, I feel like a proud parent.”

Plants of Concern—a community science program at the Chicago Botanic Garden—trains nature enthusiasts to monitor threatened plants across Northeastern, Northwestern, and Southern Illinois.

They are the unsung heroes of the conservation world: dedicated volunteers, in muddy boots and thorn-snagged pants, giving back to the landscapes they love.

“I think caring for the natural world brings out the best in people,” said Stevens.

The swollen sedge (Carex intumescens). Source: Doug McGrady.

And that care leads to wins for elusive rare species. Take the swollen sedge (Carex intumescens). Once classified as endangered in Illinois, it grows in swampy, hard-to-reach places and is easy to overlook. After volunteers began reporting swollen sedge populations in new locations, it was downgraded on Illinois’ endangered species list—one of the few times a species’ status has changed because it’s doing well, not because it has vanished.

“We update the list every five years, and we couldn’t do it without the Plants of Concern data,” said Jeremie Fant, conservation scientist at the Garden and member of the state’s Endangered Species Protection Board. “More data means more confidence, more informed decisions.”

Sometimes, volunteers help rediscover plants thought lost. Other times, like with the swollen sedge, they reveal that the species was more common than previously thought. It just needed someone to find it.

Plants of Concern volunteer monitoring rare plant populations in the Florsheim Nature Preserve.

“Not many people are out looking for rare plants in Illinois,” said Chris Benda, coordinator of Plants of Concern in Southern Illinois. “But field surveys suggest there’s still so much to find in the state. We discover something notable almost every day.”

Stevens, an English professor, revisits the same rare plants each year, marking blooms with colorful flags. He tracks their numbers, notes signs of recovery or decline, and records possible threats like encroaching invasives or deer browse. Each data point feeds into the Illinois Natural Heritage Database and is shared with land stewards to guide management.

The need for more eyes spans the state, from the Shawnee National Forest to the Forest Preserves of Cook County, both key partners of Plants of Concern. In Cook County alone, more than 550 rare plant populations stretch across the forest preserves—far more than staff can visit annually.

Volunteer finding the rare lady slipper orchid (Cypripedium reginae). Its relative, the pink lady’s slipper (Cypripedium acaule), was recently rediscovered in Illinois after 25 years thanks to Plants of Concern and partners.

Each plant monitored helps scientists understand not only what’s surviving, but why. With habitat fragmentation, invasive species, and climate change threatening native plants at accelerating rates, a single population can sound a warning or hold clues for broader recovery.

Even when a species is common elsewhere, plant populations living at the edge of their natural range, like in Southern Illinois, may carry unique adaptations that help the entire species survive.

That potential for discovery—and loss—motivates Stevens to keep returning to the field.

“You hear ‘nature preserve’ and think it’s just a nice patch of land,” Stevens said. “But there are plants that grow only here, and when they’re gone, they’re gone for good. I think I’m a good ambassador because I started out not knowing that. Now that I do, I want to help protect them for years to come.”