In the Smithsonian's Moongate Garden just off the National Mall, University of Maryland computer scientist David Jacobs pulls a leaf from a tree.
"This looks like a pretty good," he says. Then, he snaps a photo of it with his iPhone.
Moments later, the phone produces information about the tree: "This one is a katsura tree, that looks like a pretty good match," he says.
Jacobs, along with researchers at Columbia University and the Smithsonian, adapted facial recognition software to create an iPhone app called [Leafsnap](www.leafsnap.com} that identifies 191 types of tree found in Central Park and Rock Creek Park.
It'll eventually expand to cover all tree species in North America. John Kress, a research botanist with the Smithsonian, says the application could have ramifications for conservation.
"If people don't know what they're looking at, they're not going to care about conserving it," he says. "What this app does is it lets people know what they're looking at."
The Leafsnap app is free, and developers say an Android version is coming out in a few months.