Video Shows Fire Burning Through Spanish Park Covered in 'Fluff,' Leaving Green Grass Behind

A video has emerged online showing a thin line of fire burning through a Spanish park covered in white "fluff," leaving the trees and grass unscathed.

According to fact-checking site Snopes, the video first appeared online on May 6 when it was posted to the Club De Montaña Calahorra Facebook page. Over the last week, the clip has gone viral on social media, where it has racked up millions of views—in one tweet alone, the video has been viewed more 5 million times.

Local news reports confirmed the footage was taken in the Parque del Cidacos in Calahorra, a municipality in the La Rioja region of Spain located four-and-a-half hours northwest of Barcelona. According to news outlet La Rioja, the white substance covering the park that is seen burning in the video is the seeds produced by poplar trees.

"The downy fluff comprises tiny fibres that surround seeds inside the catkins of poplars and willows," Dr. Matthew Brookhouse, a tree expert at Australian National University, explained on the university's website.

"The fibres that comprise the fluff helps seed dispersal. By catching even light breezes and adding to the seed's buoyancy, fluff allows seeds to be carried far from the mother parent."

The fibers can also be highly flammable, as seen in this video. It is not clear from the video if the fire was intentionally set to remove the fluff, as has been suggested, or was an accidental occurrence.

After the clip went viral, Mayor of Calahorra Elisa Garrido settled the debate, confirming the fluff had not been deliberately set alight.

"In the Cidacos de Calahorra park there is no 'controlled burning' of poplar fluff. Every spring it is common for people with little heads (carelessly or intentionally) to cause these fires. They are very dangerous and spread quickly," Garrido tweeted.

According to local news outlet Cope, the swift response of the local fire service ensured the flames were put out, with no damage to property or injuries to residents, who until the beginning of the month were largely confined to their homes as the country only now prepares to exit seven weeks of coronavirus lockdown.

While the clip has caught the attention of people online, it is not the first time burning poplar fluff has been filmed leaving the ground beneath it apparently unmarked. A quick search on YouTube brings up several videos of people setting the fluff of poplar (or cottonwood) trees alight.