marsh gentian
noun
A Eurasian gentian of damp heaths, Gentiana pneumonanthe (rare and decreasing in Britain), which has large deep blue flowers striped green on the outside (also called Calathian violet); (also) any of several related gentians of the United States, especially striped gentian, Gentiana villosa, and soapwort, G. saponaria.
Origin
Late 17th century; earliest use found in John Ray (1627–1705), naturalist and theologian.