New Populations of the Rheophytic Macrophyte Podostemum ceratophyllum Michx. (Hornleaf Riverweed) in West Virginia

Abstract

ABSTRACT Podostemum ceratophyllum (Hornleaf riverweed) is a macrophyte that inhabits swift-water rivers with stable substrates and abundant light in montane and piedmont ecoregions of eastern North America. Within these habitats, P. ceratophyllum is considered a foundation species because the plant can strongly influence community structure by increasing habitat complexity for macroinvertebrates and fishes, and facilitates resources cycling via elemental sequestration, herbivory, and detrital pathways. Currently, the USDA and NatureServe recognize P. ceratophyllum as a conservation concern in some states, but the plant's status remains uncertain in many other states. In West Virginia, P. ceratophyllum is considered imperiled (S2) by the West Virginia Natural Heritage Program. The most recent records were collected in 1998, while other populations have not been confirmed since the late 1800s. To expand our current understanding of the distribution of P. ceratophyllum in West Virginia, we surveyed six historical sites and 34 new sites between 2015–2019. Four historical sites were found to still support P. ceratophyllum, and 10 new populations were discovered in six different river systems; however, P. ceratophyllum was not found at 26 other sites surveyed. Identifying new populations of P. ceratophyllum and resurveying previously documented populations in West Virginia expands the ecological and botanical understanding of this notably underreported plant. Improved documentation of P. ceratophyllum in West Virginia may benefit river management and restoration efforts in the state and provide insight into the plant's sensitivity to anthropogenic disturbances.