In New York City's Central Park lies a patch of lawn called Sheep Meadow, which springs to life on summer weekends with visitors tossing Frisbees and soaking up the sun. Yet like many other parts of the country, the Meadow is also alive with another, more permanent, visitor: the very grass itself.  Much of the grass on U.S. lawns originally arrived from somewhere else, but has now become a $40 billion industry, taking up space in residential yards, parks, golf courses and athletic fields. Otherwise known as turfgrass, these green spaces are expanding their reach across the country, but also stirring a debate about the environmental impact of maintaining healthy lawns.  The idea of having a patch of green is generally believed to have arrived to the U.S. from overseas. "It was a status symbol" in Europe, says Susan Barton, associate professor in plant and soil sciences at the University of Delaware. It has since become, she says, a part of the American "suburban dream."  Meanwhile, the grass itself often comes from as far as the other side of the world. The Kentucky bluegrass, for example, is originally from Europe—not the state, as its name would suggest—while Centipede grass is derived from China and Southeast Asia.  Back on the Meadow in Central Park, the grass tickling all those toes is a mixture of Kentucky bluegrass, Annual bluegrass, Perennial ryegrass and Fine fescue, according to the Central Park Conservancy. Before becoming part of the urban landscape, most of those brands came from or near Europe.
There are acres of green turf around the country, but lawn maintenance has stirred a debate about its environmental impact.