Phragmites australis, the common reed, is a large perennial grass found in wetlands throughout temperate and tropical regions of the world. It is sometimes regarded as the sole species of the genus Phragmites. Common reed commonly forms extensive stands (known as reed beds), which may be as much as a square kilometer or more in extent. Where conditions are suitable it can spread at 5 metres (16 ft) or more per year by horizontal runners, which put down roots at regular intervals. It can grow in damp ground, in standing water (up to a meter or so deep), or even as a floating mat. The erect stems grow to 2–6 metres (6 ft 7 in–19 ft 8 in) tall, with the tallest plants growing in areas with hot summers and fertile growing conditions
