A few days ago I did a post that showed my snakeroot (below). There were a lot of comments about it, and I thought I should pass on the information I have on this great plant.
In the photo below, the lantern is 4 ft tall - and the top of the bloom is about 5 ft. The plant itself is probably in the 3.5x3.5 range. I have grown it in full sun with phlox (beautiful!) and in almost full shade. I think it blooms a little better with a little bit of sun. It's a plant that likes water, but I haven't had it get wilty on me.
I don't remember the name of the green one - I've had it for about 25 years! I move it every once in awhile, and it usually breaks apart when I do, so I'm always getting new divisions - which I would guess keeps it healthy and growing.
I also have a dark one - photo above. I believe this one is called Brunette. It's a little smaller, blooms a little later, and likes more shade. The bloom is pinkish instead of white - the buds are burgundy, so it's interesting when it starts blooming and you have the burgundy and pink together.
The old name for this plant is cimicifuga - and as blackswamp_girl noted in the comments, that is a fun name, and I still use it too. In the last couple years, they have reclassified it, and it is generally under the name actaea now (not nearly as fun to say!!). Some common names are snakeroot and bugbane.
One interesting side note: when I googled it to find the new name, I found a site that said cimicifuga means "bedbug repeller" - I can honestly say I haven't seen any bedbugs in the gardens that have snakeroot in them!