Acorns are piling up around the U.S., threatening to cover some cities in nuts. Not really, but there have been an "exceptionally large number of acorns" dropped by oak trees around the country this year, Chicago-area experts say. This year has been one of the heaviest in memory for the nuts, also called "fruits" of oaks, says Kris Bachtell, a vice president with The Morton Arboretum in Illinois.
A heavy year like this, called a "mast year," is a natural, cyclical process that helps oak trees survive, and doesn't mean they're in bad shape, according to Dr. Gary Watson, the Arboretum's senior scientist and head of research.
Is the hot weather/changing climate to blame?
States were having the opposite problem in 2008 (see "The Mysterious Case of Disappearing Acorns").
Bachtell says warm, dry weather this April and May was "favorable for pollination." Data gathered at the Arboretum, a National Weather Service station, showed that April 2010 was, on average, 10 degrees warmer than April 2009. May was 3 degrees warmer, on average. Frequent summer rainfall was another factor.