The researchers studied understory plants and ant seed dispersal in 20 New York state forests that were half-old growth and half-regenerated. To disperse their seeds, several plant species depend on a mutual relationship with ants. According to Buono, northeastern North America is one of the key hotspots for ant – plant mutualism, though it also occurs in parts of Europe, South Africa, Australia, and northeastern Asia. These plants evolved with seeds that have an appendage rich in fats attached to them, and that’s very attractive to woodland ants.