Just last summer a new plant species began growing in our 7000 gallon natural pond. At first glance it looks like oblong leaves had fallen into the pond off of some tree. These leaves are attached to a long stemmed plant that has roots that almost resemble milfoil at the very base. This plant is a complete nuisance since it seems to rot very quickly and cause mold and massive clumps of algae. It seems to choke the lily pads and cause a terrible smell. We have No idea what it is and have so far been unable to identify it using the internet. Please help!

Thanks!

-Sarah in Western MA