NPSpecies

Data Source: BioBlitz, 1997-Chain Bridge Flats;Bartgis, 1993;Boone, 1986;TNC, 1999; Wiegand, 1999; Wiegand, 2001; Wiegand, 2001b; ;

Data Source: Helen Hamilton

Data Source: Helen Hamilton

Park Species Detail: Wiegand, 2001: Four (4) new and twenty-one (21) previously reported occurrences for McDowell’s sunflower (Helianthus occidentalis) were successfully documented from Sandy Hook, Maryland to District of Columbia. These occurrences vary greatly in size from three plants to nearly a thousand. Total number of plants seen during 1999-2000 field surveys is estimated at 2,000. McDowell's sunflower is not reported in Maryland from outside the Potomac Gorge section of the survey area. This is a prairie species growing erratically in the eastern U.S. Next closest sites for the species are located in northwestern Pennsylvania and southern West Virginia. BioBlitz, 1997-Chain Bridge Flats: Little Falls & upper Chain Bridge, Allen Belden, VA NHP. Prairie Savannah, Think I saw. Bartgis, 1993: State Threatened plant, in Potomac Fall-Line. Wiegand, 2001b: A previously reported occurrence for Western sunflower (Helianthus occidentalis), listed as a highly rare plant species in D.C., was successfully updated during 1999-2000 field surveys. At least 100 flowering plants were widely scattered Suitable habitat for western sunflower is abundant in the vicinity, so this occurrence could be more extensive than reported here.Status surveys for this species are highly recommended to fully determine its current status at Chain Bridge Flats Survey Site. Found at 2 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: Currently listed in Maryland as threatened and documented to occur in the gorge during this survey from Great Falls, Maryland, downriver to the District of Columbia line. Hamilton, 2007: See Helianthus dowellianus, a synonym., Park Species Data Source: BioBlitz, 1997-Chain Bridge Flats;Bartgis, 1993;Boone, 1986;TNC, 1999;Wiegand, 1999;Wiegand, 2001;Wiegand, 2001b;