In article , says...

Fortunately I had boiled the hell out of it before I ate it, boiling
removes the toxins although you are supposed to boil it twice and I only
boiled it once. I didn't have any symptoms but that's the last time I eat
any unfamiliar plant. My gardener had told me that he eats this all the
time but he is from Jamaica. I suspect that they have a different plant
that looks like pokeweed.

He probably identified it as a relative of a Jamaican variety of
pokeweed.

http://en.wikipedia.org/wiki/Callaloo

I did a bit more poking around and it's range through several varieties
runs from Canada right through South America.

http://en.wikipedia.org/wiki/Pokeweed