phrag·mi·tes 
(frăg-mītēz)
(frăg-mītēz)n.
A rhizomatous perennial reed (Phragmites australis) found worldwide, having a very tall stem with a large purplish inflorescence and often forming dense stands in wetlands.
[Latin phragmītēs, kind of reed growing in hedges, from Greek, fencing in, from phragma, fence, from phrassein, to fence in.]