yes they do! there branches will basically just fall off and will start growing everywhere in your tank also i believe. i really like it but thats why ive never bought any. on a good note though since they are such quick growers you could frag it freq. and trade them in at your lfs.
Good idea about trading them, thanks. Yeah, I think they've already started thier rampage! I just set them in that rock to see how they would look and next thing I know, they are attached and starting to spread out!