Phragmites is a emersed perennial plant that can reach 10 - 12 feet in height and shade out shorter native vegetation. It can grow along the shorelines of water bodies or in water several feet deep. In South Carolina, it is restricted to the outer coastal plain where it occurs in fresh, brackish and salt marshes and along streams, rivers and estuaries.  This plant is a native of the US and is normally not problematic.  However, there is an introduced European genotype of the plant which is highly invasive.  Recent research has shown that both native and introduced species of Phragmites currently exist in North America.  For further information about how to distinguish between the two genotypes follow this link; http://www.invasiveplants.net/phragmites/. 

    Identification: Leaves grow alternately and are two-ranked, flat, long-attenuate up to 1 1/2 feet long and 1/2 inch wide. They are blue-green in color with rough margins. The leafy stem is topped by a 1 foot long silvery brown silky panicle of flowers (shown in inset). It is capable of reproduction by seeds, but spreads primarily by underground stems called rhizomes. Growth patterns are very dense and can "crowd" out native plants which causes major ecological problems.
 

     Phragmites infestations have impacted shallow water habitat in the Winyah Bay/Santee Delta area for over three decades. The S.C. Department of Natural Resources (DNR) has battled Phragmites in its waterfowl impoundments for most of that time with limited success, but the release of a new and more effective herbicides, imazapyr and imazamox, has encouraged the agency to increase control efforts.

Go here for more detail:
2007 - 2009 Phragmites control details and maps
2005 - 2006 Phragmites control details and maps

Winyah Bay Invasive Species
Phragmites Cost Share Information!

Phragmites fact sheet
(8.5 x 11 high resolution)