gentian, (genus Gentiana), any of about 400 species of annual or perennial (rarely biennial) flowering plants of the family Gentianaceae distributed worldwide in temperate and alpine regions, especially in Europe and Asia, North and South America, and New Zealand. They are especially a notable feature of mountain regions, where the moisture-loving plants have access to underground water in summer and snow cover in winter. Gentian flowers are typically blue (hence “gentian blue”) or purplish blue but may be purple, violet, mauve, yellow, white, or even red; the four or five petals are usually united into a trumpet, funnel, or bell shape. The flowers have been used in the making of dyes, especially Gentiana pneumonanthe, a source of blue dye. The tough fibrous roots were once used herbally for putative alimentary cures, and the name gentian derives from Gentius, king of ancient Illyria and alleged discoverer of the plant’s medicinal value. Gentiana lutea, the yellow gentian, is found in Europe and western Asia and is the source of a flavouring in liqueurs.
Other species, such as the fringed gentians, formerly included in Gentiana, are now referred to as Gentianella (about 125 species) and Gentianopsis (about 15 species). The gentian family, Gentianaceae, includes 87 genera and nearly 1,700 species.