(It's the bit back left. It was too big to get in one frame.)

I think the documentation makes the case.

There may be bonsai in Japan that are in the running.

Oldest "house" plant, as an environmentally protected potted plant probably. Not "pot", as in some people might be disappointed because they thought this would be about something else.

Curious what would be the first potted house plants kept by humans, as in imported ornamental plants potted to keep them alive year round?

Chinese poems suggest that Rhapis palms were the first recorded house plant.

I have read that Aloe vera (barbadensis), also has a long history in Middle Eastern and later European cultivation. Interesting about the Rhapis in East Asia, love those too. Curiously, I too read the OP as earliest houseplants in cultivation. But getting back to the cycads, those are my oldest collected plants (mostly, Cycas revoluta), but also grow Encephalartos and Dioon. Every December, the Cycads get rolled into the garage and come out in March, Mine come out tomorrow, been doing this for decades.

The Kew specimen is possibly the oldest surviving individual pot plant. It doesn't claim to be the the earliest species in cultivation, or the longest.

Are we saying this is the oldest potted plant? Like a plant in a pot? Because it certainly isn't the kind of pot plant I'm used to lol

Yes. Pot plant in this context just means a plant that lives in a pot. Perhaps it's a British thing.

Pot means that here too. But if you say pot plant people will first think of a house plant. Note that the label at the top of the post is in Kew Gardens. They're not going to make mistakes in plant nomenclature.

I thought you meant the other kind of pot too. My perspective is the same as SherryNorthAL‘s and I’m in NY where it’s legal to have the smoking kind of indoor/outdoor pot plants. :)

Over here, we would say house plant or potted plant.

Is Kew Gardens the oldest arboretum/ greenhouse/ gardens to run continuously?

No. The oldest botanical garden in the world is in Padova, Italy. Pisa is also old. Kew wasn't founded until 1759. But it does have the largest botanical collection in the world.

Amazing that those Kew cycads look so lush at such a high latitude. Surprised they get enough tropical heat and light intensity up there. But I guess back in prehistoric days, cycads were up there growing outdoors! LOL!

They are in the Palm House at Kew, not outdoors. It's heated, lit and has high moisture levels. They wouldn't survive outdoors. But it is remarkable that this particular plant has been kept alive since the eighteenth century.

Floral, I have visited Kew Gardens. If you are ever in the northeast US, you should try to see Longwood Gardens in PA.. It’s impressive.

Flora, I realize those cycads are grown under glass, my surprise is that the light levels are adequate for robust growth, UK not known for such great sun. You said, "lit", but hard to believe artificial light can compete with the sun.

P.S., Bronx Botanical also has a nice palm/cycad court.