Last autumn I noticed several empty walnut shells scattered around our front driveway. I assumed the crows were dropping them on the concrete to break them and eat them, and didn't think much about it. However, this spring, we've come across several young walnut trees sprouting up. At first, my wife pulled them up, assuming they were weeds, but then she realized they had walnuts attached to them. A pleasant surprise because I like walnut trees! Apparently, the local crows, and probably squirrels, planted several walnuts around our home. I have since transplanted them into pots until I decide on a more permanent home for them. However, I am curious: how do I tell what kind of walnut trees they are? Because the nuts cracked open so easily (the crows dropping them on my driveway), I am pretty sure they are NOT Black Walnuts. Besides that, they could be Carpathian, Manregion, or some other species. I've walked around my neighborhood and see many other walnut trees, but don't know how to tell one species from another. Any advice?