When I was in the US two years ago, I didn't see any poinsettia "trees". What I saw was small poinsettia "plants", potted up for holiday decorations.
In Dalat, poinsettias are grown in the garden, more often at the property fence. This is what I saw the other day.
And here's my poinsettia tree, in Tuysonvien.
Christmas is coming near, isn't it?