Help Identifying tree in western Idaho

TSletten

I have an unusual tree in my back yard. It has round fruit that almost smells citrus like. They are very hard and I'm sure they are inedible o.O the seed inside is similar to a peach seed. Any ideas on what type of tree it is?

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Eden Keeper

It sure looks like a black walnut, Juglans nigra L., which is unusual for Idaho since the information I checked on the range of walnuts there shows only English walnut, J. regia L., in Kootenai county while three other species (Northern California walnut, J. hindsii (Jeps.) Jeps. ex R.E. Sm., Southern California walnut, J. californica S. Watson , and Arizona Walnut, J. major (Torr.) A. Heller, are a state or two away. Check the number of leaflets, black walnut usually has an even number due to lacking a terminal leaflet except for small(er) ones on vigorous growth, since this likely eliminates English walnut with fewer and Arizona walnut. Other keys such as chambered pith would only confirm the genus while round rather than oblong nuts with a rough rather than smooth shell respectively eliminates butternut, J. cinerea L., and English walnut. I haven't checked any further on eliminating the rest, but either way a native or naturalized rather than planted walnut (of any species) might be of interest to biologist at a university with an herbarium (plant specimen collection).

Brent Ferris

I agree with Eden Keeper that it looks like a Black Walnut - definitely outside the native range, but perhaps someone tried to plant it where you are, and so far it has survived. Usually when a tree is planted outside its native range, there is an environmental factor that limits its expansion - rainfall, drought, minimum or maximum temperatures. I would expect a very cold winter that drops to say -30 deg F and stays there for several days would likely kill the tree especially if there is insufficient snow cover.

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