Not sure if you are after a landscape in miniature or just to feature a specific specimen. I could see a mini african violet in there.

In my experience they do well in jars like that. :)

Don't want a landscape. Just a plant for interest. Its going into a well lit bathroom

Posted this pic elsewhere on GW already,but here's a look at an AV I have in a gallon jar...try to overlook the spent flower bract. :)

Here's what happens to a kalanchoe over time in a similar jar.

The leaves come on smaller when compared to a potted one in the yard.

Here's another piece of the same plant that was outside til just recently for comparison...

Just ordered 4 of these ready made - amazing quality!

https://www.theurbanbotanist.co.uk/product/tear-drop/

Here is a link that might be useful: The Urban Botanist

Most plants will quickly outgrow that jar. (Nothing wrong with that, just something for you to keep in mind. A planting in there will not likely be a long term piece.)

Mosses may be your best option. Some interesting rocks or wood pieces could be used to create a little scene or landscape. Small figurines could also be utilized if you wish.

Another plant you could use is Epipremnum 'Pincushion'. Plant only gets to be 3 or 4 inches tall and is a slow grower. Rarely see them for sale though. (On the plus side, works out for me as it makes it possible for me to sell off divisions of mine now and then. heh)

I fully agree it will over crowd very quickly and could easily be covered in a fungal infection.

Keith

Small potted cacti like being in jars for a month or two. I don't know about sealing the lid tightly though. Maybe if you open it every couple days. Sorry it's upside down.