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ST. LOUIS — It was just before 7 a.m. Friday and the conditions were perfect for spotting the elusive frost flower.

Despite the name, frost flowers are not an actual bloom, but ribbons of ice that burst out of the stems of some native Missouri plants to create beautiful and ephemeral shapes.

Only the dedicated, or very lucky, get to see them. Most frost flowers appear only on early mornings on the first few freezes of the year, such as St. Louis is seeing now.

Each flower is unique. Some look like frozen billows of smoke. Others are like pure-white cotton candy spun around plant stems. A few really do look like flowers carved in ice.

Starting Monday, overnight temperatures are expected to be chilly enough to make sightings possible again, so frost flower quests are not over for the season.

A Post-Dispatch reporter ventured out Friday to seek the icy blooms in the wild, with the help of a few knowledgeable enthusiasts.

Step 1: A science lesson

Some background research was needed before the hunt, and James Carter, a retired professor of geology and geography from Illinois State University, was the man to help.

Carter has been on a mission for about 15 years to learn about ice segregation, the process that creates frost flowers and other interesting ice formations that can spring up from things like pipes and pebbles.

Over the years, Carter has chronicled his work on his blog “My World of Ice,” in detailed posts full of scientific enthusiasm.

He provided a reporter with some of the basic rules of frost flowers:

They happen when the ground and plant root systems are not frozen, but air temperatures are just dipping below 32 degrees. Plants continue to pull up liquid from the soil, but as it leaks out through cracks in the stems and hits the air, the liquid freezes on contact. As more liquid flows, the ice builds and forms shapes.

These “flowers” are fleeting, Carter said. They typically form at night and melt within a few hours of sunrise. Moisture in the soil is essential. Even if the temperature is right, frost flowers won’t appear some years if it’s been dry.

In his retirement, Carter planted a garden with a few of the 30 to 40 plants known to spawn frost flowers and has even done experiments creating similar formations in his home freezer.

“My wife thought I was nuts,” he said. “But I wanted to know why this was happening.”

Carter also read some of the first known accounts of frost flowers. The earliest was written by scientist J.F.W. Herschel in 1833, a letter to an academic magazine with the title: “Notice of a remarkable Deposition of Ice around the decaying Stems of Vegetables during Frost.”

“People have been curious about them forever,” Carter said, “but I think in the last few years there has been quite an excitement. With the internet and digital cameras, people who see them can share pictures and ask ‘what really is this?’”

Carter maintains his blog so they can find the answer.

Step 2: The hunt

The key to seeing frost flowers around St. Louis is finding the few Missouri plants that reliably produce them. Those include dittany, white crownbeard and stinkweed, Dan Zarlenga with the Missouri Department of Conservation said in an email.

More help came from those who’ve spotted frost flowers here first-hand, including Alan Templeton, a professor emeritus of biology and statistical genomics at Washington University.

Templeton is a lifelong hiker. He spotted his first frost flower on an early morning hike about 30 years ago in Rockwoods Range conservation area in Wildwood, he wrote in an email from Israel.

For years, Templeton sought out frost flowers on cold mornings in late fall and would spend hours photographing them.

Hickory Canyons, about a 70-minute drive from St. Louis in Ste. Genevieve, is one of his favorite spots. Closer to home, Rockwoods Range near entries to the Green Rock Trail, has also remained a reliable spot, Templeton wrote.

Arriving early is key. The latest he’s seen a frost flower was 9 a.m.

“Some years are a dud, and some years are spectacular,” he wrote. “With frost flowers, you just have to enjoy the moment, which is both sporadic and ephemeral.”

Early on a recent morning, a reporter scanned a serene Rockwoods trail, with colorful leaves crunching underfoot. A bit of white from a distance turned out to be a plastic grocery bag. Alas, no frost flowers.

Perhaps a suggestion from Missouri Master Naturalist volunteer and amateur photographer Darla Preiss would produce results.

Preiss, who volunteers at Shaw Nature Reserve in Franklin County, has photographed many frost flowers, including one in the shape of a perfect heart that she spotted there in December 2016.

“It’s like a treasure hunt,” Preiss said, “Sometimes you get to see them, sometimes you don’t. I know some people are a little secretive about where they find them, but for the most part, I always want to share what I see in nature.”

A reporter followed Preiss’ detailed suggestions: Go to the Whitmire Wildflower Garden near the Bascom House. Walk down the path to the left of a half-circle of chairs and continue toward a fake bison and then to an “itty bitty tool shed” and look there.

The brisk morning walk was again beautiful and full of fall color, but only bits of frost hanging on some plants remained from what just-might-have-been frost flowers caught in the sun.

A third suggestion came from inside the city limits. Katie Stuckenschneider with Forest Park Forever, the organization that manages the city’s largest park, said the organization is often tagged in photos on social media from early morning visitors who spot the ice shapes.

One of the most reliable spots to see ice blooms in Forest Park is the Healing Garden, a short trail accessible from the parking lot at Steinberg Skating Rink. Both white crownbeard and yellow ironweed grow there and are known to make the flowers.

So about 7 a.m. Friday, with the thermometer at a perfect 24 degrees, a reporter parked in the otherwise empty skating rink parking lot.

Just a few steps on the short trail and there they were. At least 20 frost flowers dotted the pathway, looking like spun sugar or icy cocoons.

Touch one, and it feels more like snow than ice. It melts on contact.

Most of the delicate ice formations were in shadow, but a few caught in a ray of sunlight had already started to drip and go translucent.

The morning rush-hour traffic from Kingshighway Boulevard drove past, and no one else visited the little garden as the flowers dripped.

By noon, they were gone.

Erin Heffernan • 314-340-8145 @erinheff on Twitter eheffernan@post-dispatch.com

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