Phragmites australis (Common Reed) is a species complex of grasses, which occurs on every continent except Antarctica. One native supspecies. (P. a, americanus) is widespread across North America, while another, P. a, berlanderi is common on the Gulf Coast. However, a larger, densely growing and aggressive form of the reed began to spread in Northeastern North America in the 19th century, In the early 19th century, reports of Phragmites australis in developed Northeastern areas were rare,. The date of invasion is uncertain, because of the possible presence of the native subspecies. Specimens of P. a. australis were collected along the Delaware River near Camden, New Jersey in 1877, in Connecticut in 1875. and Chesapeake Bay in 1885, 1905 in Massachusetts,
Phragmites australis (Common Reed, Phragmites), appears to have native populations on every continent except Antarctica (Haslam 1972). It has probably been so affected by human transport and habitat disturbance that its original range is unknown (Holm et al. 1977; Cook 1985). As a species, it is native to North America, and has been found in 3,000 year-old peat in CT, and 1,400-1,100 year old woven artifacts in CO (Marks et al. 1994). Phragmites australis is listed here because of its apparently recent appearance (1910-1950) in many parts of the Chesapeake Bay and surrounding region, and a widespread suspicion that a dramatic increase in its abundance and invasiveness on the Atlantic Coast is due to introduction of a new genotype to eastern North America (Marks et al. 1993; Metzler and Rozas 1987; Tucker 1990; Chambers et al. 1999). Recent genetic research has confirmed this suspicion (Saltonstall 2002a).