A plant of the genus Ruppia, the sole member of the family Ruppiaceae (formerly included in the pondweed family, Potamogetonaceae), comprising plants found in shallow brackish or saline water, having thread-like leaves with small flowers borne on long, frequently coiled stems which float on the surface of the water at maturity, especially (more fully "sea ruppia") the wigeon-grass, R. maritima.
Valid publication of the genus name: Linnaeus Species plantarum (1753) I. 127.
Late 18th century; earliest use found in Colin Milne (c1743–1815), Church of England clergyman and botanist. From scientific Latin Ruppia, genus name (LinnaeusCritica botanica 94) from the name of Heinrich Bernhard Rupp, German botanist + -ia.