I gave up trying to identify the different sub-species of Elm many years ago, there's just too many of them. I have cut some outstanding Elm and you can sometimes tell if a tree is a good one as you are cutting it. About 15 years ago I harvested an Elm that was about the best tree I have ever cut. As I was cutting it I could tell that this tree was special. It was harder/denser than any other Elm I had ever cut, it literally made the blade of my little bucksaw sing. The tree was also a bit different than any other tree in that there were 2 boles growing out of the same stump. The one I had cut was about 6" in diameter but the other was only about 3" so I left it there, but I never forgot about it. The rings on that tree were very uniform with a thickness around 1/8", I have cut many other Elm with fluctuating ring thickness sometimes going from barely 1/8" to nearly 1/4" thick in only a couple feet. This Spring I decided to go and see if that tree was still standing and sure enough it was. It had grown quite a bit since I had cut its twin and was now close to 8" in diameter. I went and cut it this morning. As soon as my saw started biting into the wood I knew this tree was not the same, it didn't have the same density. Whether it has the same elasticity I don't know, I'll find that out in a year or so. I was a bit disappointed. I took a couple pictures. The first shows the stump where I cut the first tree.