Originally Posted by dasmall1
The tell-tale signs of non-aquatic plants are that it's leaves are green and white (variegated), with few exceptions, and that it can stand straight out of water. Aquatic plants are "lazy", and they can't support themselves out of water.
Like you said, for the most part, true. Anubias breaks the rule, my ammannia senegalensis breaks the rules. Those are the only two I know of for sure although I am sure there are more.
One thing about the rule also is there are a lot of plants that are grown emersed. These plants, like my ammannia will stand erect and are very sturdy but will also grow submerged like both ammannia and anubias.
There is also a marbled anubias and a couple others that are green and white. The best thing to do is keep the names with you, not only the scientific but the common names also. Also, if your LFS doesn't tell you it is not aquatic and it rots, take it back. Mine tells me so I don't have to worry about that.
When in doubt, follow the rule from Dasmall1, is the best way to put it without carrying a list of numerous plants and getting stung for a few bucks by your LFS. I just wish I would have thought of it.