I found it in a botanic garden. I believe you are right. Now the plant is bigger and the leaves seem to be of a Ricinus communis. It grows really fast.

Yep. That's Ricinus communis. Read up on toxicity issues.

Castor plant is an extremely valuable plant with all kinds of uses. The primary problem with this plant is that the sap and the pollen can cause severe allergic and/or asthma reactions. The seeds can be highly toxic if chewed up for a few minutes and swallowed, but that's another story.

I worry about that when I see stunning castor plants growing happily in people's gardens.

Stunning in more ways than one.

Just as an aside, I've grown castor bean plants every year from seed indoors and never had a problem with toxicity or allergy (and I'm highly allergic to a lot of things). I even collect the seed from the pods and save them for the following year.

I plant them at the edge of my garden fence to deter rodents tunneling, and it works.

But I don't have pets or children who might eat them.