At least two Twin Cities area fire departments are saying that the fluffy and "extremely combustible" white stuff that has been falling from cottonwood trees of late is keeping their crews busy.

"There's a bumper crop of cottonwood flying around in many neighborhoods around the city," fire officials in Coon Rapids cautioned the public in a Facebook post Saturday night. "In some cases, it's almost built up like small snow piles."

A handful of fires have been reported since late last week in yards, the post continued, that quickly spread along fence lines and houses.

"The buildup of cottonwood is extremely combustible," the notice said. It urged everyone to be cautious about discarding cigarettes, lighting recreational fires and anything else that might ignite it.

Earlier Saturday, a house caught fire in the 5200 block of W. 84th Street in Bloomington after someone set cottonwood fluff on fire.

The authoritative Twin Cities Fire Wire, made up of citizens who photograph and report on fires, said the flames moved from the exterior edges of the one-story home to woods in back before they were brought under control.

Bloomington Fire Chief Ulie Seal said Sunday that someone set the fluff on fire in an effort to get rid of it, and it spread to someone else's property.

It will be up to opposing insurance companies to sort out who will be held financially responsible, he said. No crime was committed.

Seal added that his fire crews "have had a couple of runs [recently] with that stuff in brush. ... It seems like it's everywhere."

"We've had people in the past think that the way to get rid of it is to burn it off," the chief said. "Fire runs along that stuff pretty quick."

The seasonal show begins as the female trees throw their cotton. The fibrous seed clusters are surrounded by fuzzy white fibers, giving off the look of snowflake accumulation.

Paul Walsh • 612-673-4482