Definition of marsh orchid in US English:

marsh orchid

noun

  • Any orchid belonging to any of a group of segregate species or subspecies of the genus Dactylorhiza, differing from the spotted orchids in having a hollow stem, typically purple or pink flowers, and bracts exceeding the flowers (usually with distinguishing word, as "early marsh orchid", "northern marsh orchid").

Origin

Early 20th century; earliest use found in Journal of Botany.