Phragmites (Common reed)
Phragmites australis

Infestation
Phragmite patch
Seedhead
Phragmite seedhead
 
Native to both Europe and North America, phragmite is a perennial that may grow up to 10' tall. It has been used as an ornamnetal and is often found along waterways and in marshes. It can form an impenetrable mass. It reproduces by seed, spreading stems and rhizoms. Phragmites is often confused with giant reed, but the fowering stem of giant reed is hairless while the phramites has silky hairs.