Here are a couple pictures closer up of WP that my wife had in her little cement pond. The pond looks kind of nasty now as it is end of season and she is getting ready to clean it out for the winter.
In the pictures you can see how it branches out and spreads out over the water from land based roots.
These vines covered the little pool and were taken out of the little seasonal creek as just a couple short sprigs this spring. So it has grown this much with limited soil in one year in a cement pond (plastic liner).
