Phragmites australis, known as common reed, is a broadly distributed wetland grass growing nearly 20 ft (6 m) tall

Phragmites australis, common reed, commonly forms extensive stands (known as reed beds), which may be as much as 1 square kilometre (0.39 sq mi) or more in extent. Where conditions are suitable it can also spread at 5 m (16 ft) or more per year by horizontal runners, which put down roots at regular intervals