Southern Water Plantain

Southern Water Plantain, not the Alisma triviale Or Northern Water Plantain which is considered an endangered plant in Pennsylvania and New Jersey. I just found this one Montgomery County, here near the island. It is also very near to where a major sewer line is going to be replaced.

Alisma triviale can be distinguished by its smaller (~3 mm) flowers, if
present, and the somewhat rounded or heart-shaped base to the leaves. It is similar to a Alisma subcordatum but can be distinguished by larger (~7mm) flowers, if present, and by tapered leaf bases. Thank you to this site for that information: http://research.plattsburgh.edu/wetlandmonitoring/Plant ID manual/Findit.html