Maybe Betula pubescens? It's not native and considered invasive by some sources. I don't know of any other birch that has pubescent stems.

https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/british-trees/a-z-of-british-trees/downy-birch/

paper birch are sometimes pubescent on newer growth

I too immediately thought of some species of birch. My "hybrid" Himalayan birch (sorry, but that's all OIKOS treecrops labeled/described it as) also has fuzzy stems.

I am getting a lot of new paper birch but have never noticed small ones before. So I'll go with that and keep a careful eye on them.

Thanks everybody.

Paper birch seedlings have yellow/red bark and leaves with 9 or more lateral veins. The veins on your's look more like pubescens imo.

Cordifolia didn't come up when I was searching for species with pubescent stems. I think you're correct, and it is cordifolia.

According to the references, one of the distinctions between B. cordifolia and papyrifera is cordifolia does not have hairs on the twigs.

A hybrid of pubescens and cordifolia? I don't know diddly about birches actually, or trees in general. I swear I read something somewhere about cordifolia having pubescence, but I can't find it again. The leaves do look awfully cordate though.

So, what constitutes a twig? On this sample)one year old), the main stem is very hairy. I have few others that are just the same. I have some 4 year old Birch that are mostly papyrifera, based on the leaves. But there is one among them that appears to be cordifolia. But I sure can't tell a twig from anything else. They all look alike to me.

From the https://www.minnesotawildflowers.info/tree/heart-leaved-birch site, "new growth is hairy becoming mostly hairless and shiny the second year".

But for papyrifera, "the new growth hairy but quickly becoming mostly hairless, then smooth the second year.?

What am I to believe?

I have several papyrifera 2 year seedlings here that are all pubescent and pretty consistent in having 7-9 pairs of veins. Some of their leaves are cordate. Also, the minnesotawildflowers page says that cordifolia is "restricted in range to the extreme northeastern Arrowhead region". So I'd have to conclude that if you aren't near the NE Arrowhead region, and the leaves on your trees have 9 or fewer pairs of veins, they're very likely papyrifera.

This is supposed to be pine and birch country and I'm finding lots of these young birch growing in my lower lot area where a series of Paper Birch survive. I'm happy to be getting new birch seedlings.

Nothing new grew here for 50 years or more, as the property was totally overgrown with very large oak trees, that is until I arrived and slewed them all. Now lots of new things are taking off, not just birch.