What kind of plant is this?
 

Attachment 38464

It's taking over our marsh. 3weeks ago it wasn't nearly this bad. We sprayed it but there's no way to get all of it because it seems like it never ends

Looks like "dollar weed" sometime called penny wart. 2-4d should kill it.

it looks like salvinia. Grows 1sq. foot per day in the right conditions. Alot around this time of year in slack water and bayous

Dicondria -- Spray a mix of Aquatic labeled Glysophate (roundup) and 2-4D, will take 2-3 applications to knock it out. Mix in a Adjuvant labeled for aquatic also. this helps the chemical stick to the leaf and cut through the waxy coating of the leaf