Vallisneria species
There are several types of Val, many are very common. When I think of an aquatic plant. these come to mind, I think this is the most often illustrated aquatic plant. It's a fast growing plant. I once pulled 80 plants from a five gallon hex tank. I have 4 other real nice types going American Val, Italian Val, twisted Val and a nice short growing Val. The twisted or corkscrew Val has twisted leaves and tends to stay shorter.