Arethusa is a monotypic genus of terrestrial orchids containing only 1 species, Arethusa bulbosa, which is found in eastern and central United States and Canada. It produces a solitary grass-like leaf after flowering in the summer, when it produces one (rarely 2) bright pink flower with a whitish pink labellum marked with magenta spots and a yellow center. It is typically found in acidic, boggy conditions, especially favoring a bed of sphagnum mosses. Calopogon tuberosus has similarly colored flowers and grows in the same habitat, but unlike Arethusa, its flowers are non-resupinate (i.e., the labellum is the uppermost petal).

North American Species in this Genus

• Arethusa bulbosa