Great Plains Ladies’-tresses (Spiranthes magnicamporum) in the lower Great Lakes region and a new record for New York State

Abstract

Six populations of Great Plains Ladies’-tresses (Spiranthes magnicamporum Sheviak) have recently been discovered in three locations east of the lower Great Lakes region of Canada and the United States. The possible occurrence of S. cernua × magnicamporum hybrids was detected at one New York site. These discoveries are from both natural alvar and disturbed meadow and shore sites. The new records suggest that S. magnicamporum occurs more widely than was suspected previously, its presence perhaps masked by its similarity to the common S. cernua (L.) Richard. Eastern occurrences may represent a combination of post-glacial relict populations, responses to climate change, and the results of long-distance dispersal events. These range extensions constitute the most easterly known populations of S. magnicamporum in North America. They also represent new records for New York State (including Jefferson and St. Lawrence Counties) and for the City of Ottawa in Ontario.