Cladium mariscus
Cladium mariscus is a species of flowering plant in the sedge family known by the common names swamp sawgrass, great fen-sedge, saw-sedge or sawtooth sedge. Previously it was known as elk sedge. It is native of temperate Europe and Asia where it grows in base-rich boggy areas and lakesides. It can be up to tall, and has leaves with hard serrated edges. In the past, it was an important material to build thatched roofs; harvesting it was an arduous task due to its sharp edges that can cause deep lacerations.