HISTORICAL NOTES AND NEW RECORDS FOR THE RARE ATLANTIC COASTAL PLAIN SPECIES UTRICULARIA RESUPINATA (LENTIBULARIACEAE) IN INDIANA

摘要

Utricularia resupinata is an Atlantic Coastal Plain relict of the aquatic vascular flora of Indiana and is one of 10 species of bladderwort found in the state. This species was thought to be extirpated from Indiana until it was rediscovered at a historical locality in 2005. We document two additional populations of this species in Indiana and report on the status of all known historical localities in the state. Six palustrine sites in Lake County and nine lacustrine sites in northern Indiana were identified and surveyed; however, no extant populations were found. We provide a historical synopsis of alterations to wetland habitat in Lake County and identify habitat destruction as the main contributing factor leading to the loss of U. resupinata from these palustrine sites. Although suitable habitat appeared to be present at most lacustrine sites, several other factors may be important in contributing to the perceived rarity of this species. Inadequate sampling techniques, which include a tendency to confine searches for this species to shoreline habitats instead of deeper areas of the littoral zone, the use of in-boat aquatic plant survey methods, and an over-reliance on flowering material for identification of a species that seldom flowers, have contributed to a greater perception of rarity than may actually be present. In contrast, competitive exclusion by larger aquatic plants and charophytes may provide an ecological explanation for the rarity of this species in some locations.