VALERIAN, a genus of herbaceous perennial plants of the natural order Valerianaceae. Two species—Valeriana officindis and V. dioica—are indigenous in Britain, while a third, V. pyre naica, is naturalized in some parts. The valerians have opposite leaves and small flowers, usually white or reddish, and arranged in terminal cymes. The limb of the calyx is remarkable for being at first inrolled and afterwards expanding in the form of a feathery pappus which aids in the dissemination of the fruit. The genus comprises about i so species, which are widely dis tributed in the temperate parts of the world. In medicine the root of V. officindis is intended when valerian is mentioned.
Valerian is cultivated in England, but to a much greater extent in Saxony, in Holland and in the United States. The dried root or rhizome consists of a short central erect portion, about the thickness of the little finger, sur rounded by numerous rootlets about -- of an inch in diameter, the whole being of a dull brown colour. When first taken from the ground it has no distinctive smell; but on drying it acquires a powerful odour of valerianic acid. This odour, now regarded as intolerable, was in the i6th century considered to be f rag rant, the root being placed among clothes as a perfume (Turner, Herbal, 1568, part iii. p. 76), just
as V. celtica and other species are still used in the East.
The 'red valerian of gardens is Centranthus ruber, also belong ing to the Valerianaceae ; but Greek valerian is Polemonium coeruleum, belonging to the f am ily Polemoniaceae. Cats are - - - - - - - - nearly as fond of the smell of this plant as of the true valerian, and will frequently roll on the plant and injure it.
The chief constituent of valerian is a volatile oil, which is pres ent in the dried root to the extent of 1-2%, plants growing on dry or stony soil being said to yield the largest quantity. The oil is of complex composition, containing valerianic (valeric), formic and acetic acids combined with a terpene, CioHis; the alcohol known as borneol; and pinene. Valerian acts medicinally entirely in virtue of its volatile oil, which exerts the actions typical of its class. The special use of this drug, like that of others which con tain an offensive volatile oil—such as asafoetida—is in hysteria.