Look up yellow nutsedge and mace sedge. Broomsedge is another one. The leaves have steps vs flat n smooth. Where the leaf node is more distinct than grass in triangular shape.
Sedge often grows in areas where its wet long enough for most other things to die.
Sedge hunkers down in root nodes. Usually takes several whacks to destroy. Eliminating is difficult. Several hits of roundup usually puts it in the background.
Sedge is a warm season plant. Attacking early or late in the season helps alot. I use basagran, then in 2 weeks use roundup before planting in my camp foodplots. Asuming I can get there and the weather cooperates. Clethodim is useless against sedge. Adding some 2,4D can help.
My high organic matter sand at camp holds moisture well despite some sandy soils. Combine that with alot of snow melt in the spring and a bit extra rainfall from being near the great lakes, and sedge becomes king there.
Adding some alternate plant life after spraying rounds helps some too.
Sedge does not need the bacteria other plants do to survive.
Trick is to drain the roots of energy, especially before it dries out for awhile. Kill the leaves, the roots use energy to make more. kill those again, and some roots start to die. Stuff behaves alot like chufa. chufa is a sedge.