Phragmites australis invasion alters the structure and function of diverse marsh ecosystems by changing species composition, nutrient cycles and hydrological regimes. Dense Phragmites stands in North America decrease native biodiversity and quality of wetland habitat, particularly for migrating waders and waterfowl species.

Though some populations of Phragmites australis may be native to parts of New England, it becomes problematic when it forms huge monocultures that spread for acres, excluding native species. This often happens when it grows in polluted areas that other plants do not tolerate as well. It can form large, thick walls at the interface of upland and wetland habitats. In New England it is clear that this plant has spread beyond its original range, and is now encroaching into wetlands that contain rare native species.

Control Methods
Recommendations for Phragmites control include the use of herbicides, mowing, disking, dredging, flooding, draining, burning, and grazing. The most widespread and successful approach on National Wildlife Refuges appears to be the application of glyphosate late in the growing season, followed by prescribed burning or mechanical removal of dead stalks (These herbicides can only be applied by a licensed herbicide applicator!). One reason for the reliance on chemical control is that habitat management such as cutting, mowing and disking actually encourages the spread of Phragmites.

Click here to learn about the ongoing efforts of the Spruce Creek Association to control this aggressive invasive.

Key Identifiers
Phragmites australis is a stout grass that measures 2-4 m (6.5-13 ft.) in height. It is most often seen in large colonies. The stems and leaves are smooth and glabrous. The gray-green leaves are acuminate in shape, 25-50 cm (10-20 in.) long and 2-3 cm (0.75-1 in.) wide. Long white hairs are present at the leaf-sheath junction. The light brown to purple inflorescence is 20-40 cm (7.5-15 in.) long. The spiklets have 3-7 flowers and appear between July and September. The flowers are surrounded by silky white hairs. The first glume is narrowly elliptic and blunt, while the second is linear and nearly twice as long as the first. The lemmas are narrow, 8-12 mm (0.3-0.5 in.) wide. The rachilla hairs are white and as long as the lemmas. However, they are not visible until after the flowers bloom. The seeds are brown, light weight, and about 8 mm (0.3 in.) long. In the fall the plant turns brown, and the inflorescences persist throughout the winter. Phragmites australis can grow in a variety of habitats. It is most often found in wet or marshy areas. This plant grows best in fresh water, but also can be found in brackish, acid or alkaline wetlands. It is also found at the interface between wetlands and uplands.

Reproductive/Dispersal Mechanisms
Phragmites australis reproduces by means of wind-dispersed seeds and by long rhizomes.