The Skeleton of a Leaf

I saw two old leaves in the driveway this afternoon.  They were about 6 inches in length.  When I picked them up, what was amazing was that there was almost nothing left of the leaves - just a delicate tracery.  I was astounded at how delicate it all was.  Then the mystery to me was how this structure managed to survive.  I realize that when you turn a leaf upside down, you can see this structure, when the leaf is all green. So apparently the "stuff" that holds the chlorophyl is more delicate and disintegrates, while this structure does not.  Please click on the image to see it in more detail.