NPSpecies

Data Source: TNC, 1999; Wiegand, 1999; Wiegand, 2001; Wiegand, 2001b;

Data Source: Helen Hamilton

Data Source: Helen Hamilton

Park Species Detail: Wiegand, 2001: Seven new and six previously reported occurrences for Scarlet ammannia (Ammannia coccinea) were documented during 1999-2000 field surveys (from Sandy Hook, Maryland, to District of Columbia line. A total of nearly 400 plants were counted in the survey area during this survey. Most of these occurrences contain between 10 and 30 plants. The largest occurrence on Falls Islands contains an - estimated 100 plants. Scarlet ammannia may only occur along the river during dry years when low river levels expose edge, scour bar and drawdown habitats. Wiegand, 2001b: A previously reported occurrence for Scarlet ammannia (Ammannia coccinea), listed as a highly rare plant species in the District of Columbia, was successfully updated during 1999-2000 field surveys. Two groups of plants were seen. A preponderance of nonnative weeds on Chain Bridge Flats represents a serious long-term threat to the rare plant species. Found in Fletchers Floodplain Survey Site. Wiegand, 2001: Seven new and six previously reported occurrences for Scarlet ammannia (Ammannia coccinea) were documented during 1999-2000 field surveys. A total of nearly 400 plants were counted in the survey area during this survey. Most of these occurrences contain between 10 and 30 plants. The largest occurrence on Falls Islands contains an - estimated 100 plants. Scarlet ammannia may only occur along the river during dry years when low river levels expose edge, scour bar and drawdown habitats. Found at 3 sites; A Highly Rare plant species known to occur within the District of Columbia portion of LOCO (along the C&O Canal NHP and Potomac River from the Maryland line to Key Bridge, Washington, D.C.) Also a listed species in Maryland. Wiegand, 1999: Documented to occur in the gorge during this survey from Great Falls, Maryland, downriver to the District of Columbia line., Park Species Data Source: TNC, 1999;Wiegand, 1999;Wiegand, 2001;Wiegand, 2001b;