Actually I agreed with your opinion that the first two photos are C. aquatica according to the book”Neue Wasserpflanzen-Praxis” from German botanists Gerhard Brunner and Peter Beck. While all these books we have mentioned are very old, the first time I heard the voice that C. aquatica is not C. australis came from the book “The World’s Waterplants”(sorry , it doesn’t have an English name, the ISBN No. is 4-7952-3012-9 C0345 P2200E, please check it out)written by Yamasaki and Yamada (1994), it said that the distributions of these two plants are different although they look very similar to each other, and the most important discrimination of C. australis compared to C. aquatica is that the starting point of the pinnae fragment is red-purple, not yellow, meanwhile the pinnae are shorter but wider, therefore C. australis is smaller than C. aquatica. Both of their flowers are yellow, but the laminae of floating leaves are round in C. aquatica., lanceolate in C. australis, so if this is true I think maybe you are right because I remember that the plant in the photo did grow round floating leaves.
Hey, is the Cabomba caroliniana 'Silver-Green' really existent in your market now?
Would you please show me a clear photo of it ? My friends here seem not to believe my report that it is real!