In another thread I asked for advice pruning this young tree that I mistook for a black walnut. I thought it was black walnut because it propagated, volunteered in a pot, on my forest property just outside of Berea, (central) KY. It's oak-hickory forest. Chestnut oak is the dominant oak and had three types of hickory, also several types of maple mostly in the understory with sassafras, dogwood and redbud. The only pinnated compound leaves were on black walnut and Kentucky coffeetree. The leaves were wrong for Kentucky coffeetree, so black walnut is what I thought it was.

Now that someone has asked about it, I've realized it cannot be a black walnut because black walnut is only odd-pinnate and some of these leaves are even-pinnate. The leaves were bright red last fall and black walnut has very little color. It's also growing a bit fast for a black walnut, 3'+ already this year.

Now I need help with the ID. Someone suggested sumac, but the types of sumac which grew in that area aren't like this tree, they are more shrub-like. It's possible the seed came in from a bird. I had a couple of very active feeders that attracted a wide range of birds.

Here's a picture of the tree I posted earlier:

Leaves are pinnated compound with up to 28 leaflets. There are both odd-pinnated leaves:

And even-pinnated leaves:

When I first looked at this tree I thought the compound leaves were opposite:

But some of them look alternate:

The stem of the leaf is a funky purplish color.

Sumac was one person's suggestion but it didn't have any of those big red flowers last spring, though it was only a single 36" stick when it sprouted this spring so maybe it hadn't set any buds. I don't know enough about sumac to know if they set buds only on previous year's growth.

Smooth sumac, Rhus glabra, was another suggestion, but it only grows to 15' and this tree is already pushing 7' in its first established year.

Kentucky has the national champion shining sumac, but Rhus copallinum has winged leaf stems which my tree does not.

I can see where this could be a sumac, but what kind? Or is it something else entirely?