How to Identify Walnut Tree

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?

 

Hmm, I wonder if mature leaves will be required.

 

Here is a superior and contemporary treatment:

http://www.dendrology.org/publications/tree-profiles/notes-on-the-temperate-species-of-juglans/

 

How many leaflets per leaf? Persian Walnut has 5-7 (rarely 9), other walnuts have 9-11 or more.

 

Attached is a photo of one of them.
(They might still be too young to identify.)

 

I took a walk around my neighborhood and came across an old Walnut tree about five blocks away from my home. I chatted with the owner of the lot for a while and she told me the tree has been there since before they bought the lot--over 35 years ago! I am attaching four photos because it doesn't seem like a typical Walnut tree and would like some help identifying it. The trunk is light-grey or silver. The leaves are made up of 9 leaflets and are very big and round, almost like ellipses (not like the spearhead shape I am accustomed to seeing.) The green husks are not completely round, but somewhat oval, coming to a point at the tip. Some empty shells on the ground confirm the shape of the shell: like an oval that is squished to a point at the end. Any ideas what kind of walnut tree this is?

 

Not sure why no one has replied to the last post yet. These remind me of butternut, Juglans cinerea, although they are supposed to have 11-15 leaflets typically.

 

Large leaflets with a jumbo one at the end of the leaf + ovate fruits = one of the Asian species to me. There are landmark specimens of these in nw WA so it seems they might not be unexpected in the Lower Mainland.