Good question,,,, I'm intersted too.

I've never heard they're poison... this link says they're interchangeable with banana leaves, I'd think they would be more tender, so you'd have to use more, or maybe wrap tin foil around them after the leaves...http://chowhound.chow.com/topics/505854

And in South America they eat the rhizomes- grind it into flour for thickeners.

Thanks, Silversword - I'll give it a try!

It would probably be ok as a wrapper but I doubt if canna leaves would provide the flavor banana leaves do. But it would be interesting to find out. I use basjoo leaves once and I don't think the aroma is as strong as leaves from other edible banana.