Can you identify this seedling?

[bowtarist]

Yup, cottonwood seedling. What's the leaf litter on the ground around the big tree look like? dp

[Thesquirrelslinger]

that, my friend, is either cottonwood or Chinese pear.
the leaves are nigh on identical, and I have seen both in person many, many times. cottonwood cause its in the arboretum nearby.
Chinese pear is a highly invasive species and a very popular shade tree.
I have personally ripped out almost an entire acre of chinese pear seedlings about 1-2" in diam. its nasty work.
that is definitly NOT red oak- red oak has oak-shaped leaves.

that is red oak.

[crooketarrow]

 The seeding looks like our SCYAMORE. I don't know what the tree is. It's not sycamore tree.

[wapiti1997]

It is 100% cottonwood.. a wind blown seed...

[bubbles]

I think the red oak was in reference to the full tree which did not have leaves,  not the seedling.

[bobnewboy]

If you were in the UK, I would say its almost certainly Poplar.  Perhaps with a very outside chance of being Silver Birch.