Your first and second pictures have what looks very much like Hydrilla verticillata
, a plant which is on the Federal Noxious Weed List.
If it has thorns on the underside of the midrib of the leaves as shown in the picture, it is definitely that, and should not be sold or distributed. Of all the aquatic plants on the Noxious Weed List, this is one of the most damaging when it gets loose.
Your last picture shows Rotala rotundifolia
. The next to last picture also shows the Rotala
, but with a mat of Riccia fluitans
growing on top of it. The one before that also shows the Rotala