As their name suggests, these normally grow in tidal saltmarshes, which we do not have in Philadelphia. The closest saltmarshes are on the other side of John Heinz, the Philadelphia side of which is generally freshwater marshland. I found these under I95, where the run-off from the excessive salting of the elevated highway seems to have created a strip of saltmarsh along it. The plants were only found almost directly under the highway. I could find none more than 15 feet from the highway.