��ɫtv

They are found most often in the Eastern half of the U.S., especially in the upper half where hard freezes are more common, and resemble clouds of cotton candy or spun glass.

For some, it’s become a well-known phenomenon, indicating the nearness of winter and ushering people out of bed to get a glimpse before the day’s sun melts them away.

On Monday and Tuesday, people in Indiana, Missouri, Tennessee and elsewhere posted photos on social media showing undisturbed fields and backyards littered with the distinct pieces of natural art in the early hours after the hard freeze.

“You have to be at the right time, at the right place,” said Alan Templeton, professor emeritus at Washington University in St. Louis, Missouri, who does a lot of conservation genetics. “You see them and you know they’re going to be gone in an hour or two. So it’s this very ephemeral, but highly variable beauty, and it’s that combination that makes me so fascinated by them.”

While the intricate ice patterns are found near the base of a few common plants, including white and yellow wingstem plants, Templeton explained that the conditions need to be just right for them to appear. And once they do, they won’t be back for another year.

The ground must be warm and wet enough for water to travel up from the plant’s roots into the stem, while the air needs to be cold enough to freeze the liquid so that it breaks through the stem, creating the flower-like appearance.

They’re only found on a few different types of plants because the phenomenon can only occur if the stem is able to hold water in the fall or early winter and is weak enough to break against the pressure from the ice, he said. The plants also need to have an especially active root system later in the year.

Templeton said he first came across frost flowers decades ago while scoping out an area in the Missouri Ozarks for field work.

“They’re really beautiful,” he said. “And also each one is unique. There’s no two frost flowers that are the same.”

On Monday, after noticing that the weather conditions would be ripe for the phenomenon, he set out for a conservation area in St. Louis County where he’d found hundreds in past years. This time, there were only about two dozen, which he said was likely due to them appearing earlier than usual and the temperatures not dipping quite low enough.

Crystal Legens has lived in Tennessee for most of her life but said she only discovered frost flowers three years ago when her family moved into a more rural part of the state.

After seeing them along a small unmaintained tract of land while driving to work in McKenzie, some 47 miles (75 kilometers) northeast of Jackson, she said she initially thought they were spider webs or silkworms. When she got out of her car and picked them up, she said they broke apart in her hands.

“People live here their whole life and they never even know that exist because they just never see them or they’re not in the right place at the right time,” she said.