Heres a quick question on the make up of a white oak tree (well any oak tree for that matter)....

Say for instance we have a 100 year old white oak tree, thus it will have 100 tree rings on the trunk if we were to cut it. Out of those 100 tree rings, how many of them are actually responsible for transporting water through out the tree. And, of those rings that transport water, are they on the inside of the rings (the middle of the tree) or the outside (near the bark)?