Pete Leki rubs the papery yellow and green leaves of prairie gentian across a sieve, releasing a spray of tiny golden seeds into a big metal bowl.

Leki and his son, Jamal, begin to sing, and two women join them in a Japanese hymn to Mother Nature.

“In the bosom of our mother/We children of earth find our joy.”

The impromptu performance added to the bustling scene inside a garage at the Emily Oaks Nature Center in Skokie. As they’ve done for over 30 years on the weekend before Thanksgiving, volunteers from the North Branch Restoration Project have gathered to process seeds that they’ll return to the soil.

Most of the roughly 50 participants work over tubs, separating seeds from chaff.  Three kids in trash cans stomp the spiky, seed-bearing heads of rattlesnake master, a denizen of wet prairies.

In all, the project will supply 100 gallons of seed to volunteer stewards who tend lands along the Chicago River’s north branch. They’ll plant natives like wild quinine, bluejoint switch grass and cress on land that’s been cleared or burned.

Seed distribution is an important part of preserving biodiversity, the rich variety of biological life that promotes healthy ecosystems, says Jane Balaban, a master steward with the Cook County forest preserves.

“Insects love the little clumps of flowers on rattlesnake master,” says Balaban. “And of course, the insects pollinate other plant species. It’s part of that network, that web of biodiversity.”

Some of the best remnants of native prairie and woodland in the state are found in the Chicago area. Since the late 1970’s, a growing army of volunteer stewards have been working to restore these ecosystems in the Forest Preserves of Cook County and other public lands.

That's why you’ll find many of these seed-processors in area preserves on weekends. They clear brush and cut invasive species like buckthorn and garlic mustard, which crowd out native plants.

John Balaban, Jane’s husband, sits on a folding chair, like a director.  He oversees the division of seeds into 12 garbage cans, each holding a different seed mix that’s been precisely blended to thrive on varying amounts of sunlight and moisture.

“You can see the range of ecosystems,” says Balaban as he points to the cans. “From high quality prairie to mesic open savannah, wet mesic open savannah, open woodland, woodland, all the way to pond.”

Stewards are very careful about where they gather their seed, says Jane Balaban. Nothing is planted that wasn’t here before European settlers disrupted the native ecosystems.

And they strive to preserve the integrity and specificity of the local habitat.

“We want to keep the local genotype, so we have a limit of maybe 15 miles for where we collect prairie species, 25 miles for woodland or savannah species,” says  Balaban.

Susan Checchia, who monitors butterflies at two prairies in Morton Grove, is seed-processing for the first time.

Earlier, she says, she was separating seed from the ironweed plant—“kind of a shrub with real pretty little delicate purple flowers.”

 “I noticed in early to mid-summer, the skippers, a type of tiny butterfly, flock to this plant and decorate it like a Christmas tree,” says Checchia.

Julie Peterson, who volunteers in the Sauganash Woods, strikes a match and burns off the milky fluff inside the pod of a butterflyweed, exposing the brown seeds.

Peterson says that the work doesn’t carry the same cache as trying to save the peregrine falcon or the spotted owl.

“Still, some of these seeds are so rare, and they’re incredibly precious,” says Peterson. “Even a really small grass seed can be endangered or threatened and it can be just as critical to the ecosystem.”