My guess would be either a dawn redwood or a coast redwood. But at that stage, I find them pretty difficult to tell apart :-) You'll know if it loses all its needles........

I think it's baldcypress, Taxodium distichum.

Seeing what I believe are alternate leaflets.

https://www.montgomeryohio.org/hi/baldcypress-is-city-arborists-favorite-tree/

Agree with bald cypress.

Thanks everyone! Looks like bald cypress based on googling. The needles are also changing color. I wasn’t aware that conifers can be deciduous until I began researching this tree. Is this a tree that I could grow in a pot on my balcony?

Balcony? In your searching, did you see images like THIS?

tj

Yup, but I have a pretty large balcony! Just kidding. I think the short answer is “yes”, and the better answer is “yes, but it’s going to take some education and work”. This isn’t the right forum for a deep dive into my question, but I’ve gotten so many really helpful bits of practical information woven among the responses, I didn’t think before asking. I’ll poke around in a couple of forums that are more on topic.

Anything can be grown in a container..........at least for the short term. But growing a tree in a container long term will take some extra effort, especially a tree that wants to grow large. Soil media, proper fertilization, repotting and root pruning, winter protection will all require some significant research on your part.

I'd suggest spending some time in the Container Gardening forum, reviewing the discussions about soil mixes, water movement and most particularly, growing trees in containers.

Thank you!

Update: Didn‘t someone once say there are no failures in gardening only experiments? This was definitely an experiment. As it turns out, my balcony was far too windy for this sapling but I didn’t notice in time to move it to a more sheltered spot before some branches were torn off. I put it back in the ground. Fortunately the experiment will continue with a rhodie and different conifer that seem to handle the conditions better. I don’t know what they are. I found the conifer in a small pot in my Dad’s garden. It was about a foot tall at the time. The rhodie was planted stealthily a few months ago in an area of my apartment building‘s landscaping that contains several other (but different) rhodies. If the person had done a better job, no one would have noticed until it bloomed. Apparently that sort of thing happens periodically.