Should I collect seed? What do seeds look like? Should I dig up the plant? I have native plants on my land and would like to create more in another spot.
Here are some differences between the native and non-native phragmites in the articles below. Be sure you have the native variety, which is harder to find. You can increase the native stands by digging up and dividing an existing stand and replanting the divisions.
https://www.gardeningknowhow.com/plant-problems/weeds/phragmites-native-vs-invasive.htm
https://mnfi.anr.msu.edu/pdfs/phragmites-native-non-native.pdf