Looks like water primrose maybe. Usually grows around the edge in not over a few feet water depth.

Aquatic glyphosate will get both. Regular roundup will but it is not approved for water because of the surfactants used on account of fish and other aquatic amimals. The aquatic version is available at places like Tractor supply and will work if you can get to where you can spray it.

If there are fish and you are concerned about them be aware that if you kill too much plant material all at once it can cause a low disolvable oxygen situation and potential fish kill. This is normally a problem later in the season with hotter temperatures. If it is a concern the solution is to only treat a smaller area (like 1/4 of the pond) then treat another area a few weeks later after the first has died and degraded. In other words don't treat the whole pond at once and have all that dead material taking up oxygen all at once.