Any of the more than 400 species of annual and perennial herbaceous plants in about 10 genera that make up the family Valerianaceae.
A few are outstanding as ornamentals, salad or potherbs, or as sources of medicines and perfumes. Greek valerian is Jacob's ladder ( Polemonium caeruleum ), in the family Polemoniaceae. The true valerians (native to the temperate zones, the Andes Mtns., and Africa) have tubular flowers, often spurred at the base and clustered in tight heads. The largest genus, Valeriana , contains about 200 species and is best known for common valerian ( V. officinalis ), used by modern herbalists to calm the nerves.