Osage Orange (Maclura pomifera) male

Newark, DE (Probably June since it was so late to leaf out)
It has thorns of the size and location as required.
It also has the orange-tinted underbark.

Although I've seen no mention of it, these trees were the latest to leaf out that I could see.

I suspect the Oak at Newark Oaks leafed out prior to these trees,
but I'd have to check on that again next year.

The entire line of trees leafed out from the bottom up - not all at once, or top down, but from the bottom up in strict succession.

It has an interesting leaf-growth pattern that I've never noticed before on any other tree.
It seems to get two sets of leaves. It sets its first leaves when it begins to green, then, after some time when the new growth starts, the "2nd" set of leaves that opens up looks different. At first I thought I was seeing different trees leaving out, but, no, it's the second set. These also started leafing out from the bottom up giving the entire row of trees the appearance of being taken over by other trees with larger leaves. It's now near the middle of June (today's the 12th) and the 2nd set of leaves, on the one tree I'm watching most closely, is within about six feet of the top.

These trees are about 60 feet tall.

Update 6/30/14. I take it back, I think the trees are closer to 75 ft high.
Have been watching the leaf progression closely and the last few of the recalcitrant tops of the tallest trees are now showing a "new" 2nd set of leaves also. I can still see a difference because I've been watching, but I doubt that anyone else would notice much of difference if they were just taking a casual look around.

Update 10/18/14. The first few "oranges" started to drop about the third week in July. They started falling in earnest about mid-September. They are still falling. An occasional huge and hollow "thunk" when I'm outside tells me that one has fallen on a car.