Ecological Risk Screening Summary - Vallisneria natans (an eelgrass, no common name) - Uncertain Risk

Species that are considered uncertain risk need a more in-depth assessment beyond the Ecological Risk Screening Summary to better define the species’ risk to U.S. environments.

Vallisneria natans, a species of eelgrass, is a submergent aquatic plant native to Asia and Oceania. It is present in the aquarium trade, going by the trade names ‘Contortion/Contortionist’ or ‘Corkscrew’ tapegrass or ‘Val,’ although it may be less common in trade than other members of the genus. Vallisneria natans is also used in vegetation restoration efforts within its native range and as a medicinal plant in Vietnam. This species reproduces both sexually and asexually. The History of Invasiveness for Vallisneria natans is classified as No Known Nonnative Population due to the absence of reports from the wild outside of its native range. The climate matching analysis for the contiguous United States indicates establishment concern for this species. The climate match was highest in the Northern Plains, western Great Lakes, and Southern Atlantic Coast regions. The Certainty of Assessment for this ERSS is classified as Low because of the lack of information on impacts of introduction, in addition to taxonomic uncertainty and incomplete trade history. The Overall Risk Assessment Category for Vallisneria natans in the contiguous United States is Uncertain.