JUNCUS VALIDUS COVILLE (JUNCACEAE) NEW TO THE GREAT LAKES REGION

摘要

Significance of the Report. The first reports of this species from the Great Lakes region, including Ohio and Michigan. Previous knowledge. Juncus validus Coville (roundhead rush) is a perennial wetland generalist of the south-central and southeastern United States. Prior to 1900, the species was known from a relatively restricted area of Oklahoma, Texas, Arkansas, and Louisiana, with one outlying (and likely non-native) population in Mississippi. From this putative natural range, J. validus has since spread east and north across the southeastern United States to Maryland and Delaware (Knapp 2014). These eastern populations have been conflictingly interpreted as native and of conservation concern (Kentucky and North Carolina) or as non-native (Delaware, Maryland, and Virginia) (NatureServe 2017). Rangewide, J. validus is considered globally secure (G5) by NatureServe (2017). Discussion. Two small patches of Juncus validus were documented in 2008 along a moist to dry sandy road created by off-road trucks in Lucas County, Ohio. The population persisted through 2009 and was not found in 2010. In 2011, a new population of 70 plants was found approximately 300 meters from this location in a palustrine sand plain wetland created in 2010. This population expanded to over 100 plants in 2015. The species has not reappeared in the original location, which has become much drier and is apparently no longer periodically saturated.