Question
I found some huge seed pods in Central Park (NYC) over the weekend, similar in look to that of a sycamore, but the size of a grapefruit or large orange. They were green, with an uneven surface, slightly sticky. Inside they are white dry pulp, and built the way a sycamore seed pod is but MUCH bigger. I didn't take the leaves around it, and couldn't identify the tree above them, as it was in a woody area on a hill. What tree was it? I brought a pod home and took it to my daughter's school, and now I am hoping the class can help identify it and get more information about trees and their seeds. Any information to identify the tree and/or direct me to more helpful sites would be great. Thanks!

Answer
This sounds like Osage-Orange, Maclura pomifera. Known also as hedge, hedge-apple, bodark, bois-d'arc, bowwood, and naranjo chino, it made agricultural settlement of the prairies possible (though not profitable), led directly to the invention of barbed wire, and then provided most of the posts for the wire that fenced the West. The heartwood, bark, and roots contain many extractives of actual and potential value in food processing, pesticide manufacturing, and dyemaking. Osage-orange is used in landscape design, being picturesque rather than beautiful, and possessing strong form, texture, and character.

OsageOsage oranges are members of the mulberry family, meaning that they are not true oranges. The fruit produced by OsageOsageOsage orangeorangeorange trees does look like an orangeorangeorange, especially at a distance, but it is inedible. Although their fruit cannot be eaten, OsageOsageOsage orangeorangeorange trees have a number of uses, and they can be found throughout the American South and Midwest. Some garden supply stores sell OsageOsageOsage orangeorangeorange seedlings, for people who wish to plant these distinctive ornamental trees.

The fruits which they produce are large and heavily wrinkled, reminding some people of the brain. Because the fruits endure after the leaves fall off, you can spot an Osage orange in the fall from quite a distance, thanks to the large, brightly colored fruit. When cut open, the fruit proves to be pulpy, pithy, and slimy, making it totally unappetizing to all but the most desperate squirrels. The odd appearance of the fruit has inspired nicknames such as brainfruit, monkey ball, and monkey brain.
Here is a web site with pictures.
http://www.gpnc.org/osage.htm