Definition of marsh orchis in English:

marsh orchis

noun

rare
  • (Originally) a supposedly single orchid species of the genus Orchis found in marshes and damp meadows in Europe, later recognized as comprising two or more species and subspecies (now placed in the genus Dactylorhiza); (in later use) any of the segregates into which the ‘marsh orchis’ (as originally understood in Britain) was divided.

Origin

Early 19th century; earliest use found in John Vaughan Thompson (1779–1847), surgeon and naturalist.