GENTIAN, botanically Gentiana, a large genus of herbaceous plants belonging to the family Gentianaceae. The genus comprises about 400 species—most of them plants with tufted growth, growing in hilly or mountainous districts, chiefly in the northern hemisphere; but they are absent from Africa. The leaves are opposite, entire, smooth, and often strongly ribbed. The flowers have a persistent to 5-lobed calyx and a to 5 lobed tubular corolla ; the stamens are equal in number to the lobes of the corolla. The ovary is one-celled, with two stigmas, either separate and rolled back or contiguous and funnel-shaped. The fruit when ripe separates into two valves, and contains numer ous small seeds. The majority of the genus are remarkable for the deep or brilliant blue colour of their blossoms, comparatively few having yellow, white, or more rarely red flowers; the last are almost exclusively found in the Andes.
Only six species occur in Great Britain. G. Amarella (felwort or autumn gentian) and G. campestris are small annuals growing on chalky or calcareous hills, and bearing in autumn tubular pale purple flowers ; the latter is most easily distinguished by having two of the lobes of the calyx larger than the other two, while the former has the parts of the calyx in fives, and equal in size. Some intermediate forms between these two species occur, although rarely, in England ; one of these, G. germanica, has larger flowers of a bluer tint, spreading branches, and a stouter stem. Some of these forms flower in spring. G. Pneumonanthe, the Calathian violet, is a rather rare perennial species, growing in moist heathy places from Cumberland to Dorsetshire. Its average height is from 6 to 9 in. It has linear leaves, and a bright blue corolla I2 in. long, marked externally with five greenish bands. It is the handsomest of the British species; two varieties of it are known in cultivation, one with spotted and the other with white flowers. G. verna and G. nivalis are small species with brilliant blue flowers and small leaves. The former is a rare and local perennial, occurring, however, in Teesdale and the county of Clare in Ireland. It has a tufted habit of growth, and each stem bears only one flower. It is sometimes cultivated as an edging for flower borders. G. nivalis in Britain is very rare and occurs only on a few of the loftiest Scottish mountains. It differs from the last in being an annual, and having a more isolated habit of growth, and in the stem bearing several flowers. On the Swiss mountains these beautiful little plants are very abundant, and are one of the striking floral features of the Alps. For ornamental purposes several species are cultivated.
About so species occur in North America, widely distributed throughout the continent, but most numerous in the Rocky Moun tain region. Of some 15 species found from the Great Plains east ward, among the best known are the fringed gentian (G. crinita), one of the most beautiful American wild flowers; the closed or bottle gentian (G. Andrewsii), the most common species; the downy gentian (G. puberula), of the prairie region; and the stiff gentian or ague-weed (G. quinque flora), which extends southward to Florida. Of the many Rocky Mountain species, those with fringed flowers, as G. elegans and G. barbellata, are among the most conspicuous. Representative of the 12 or more species found in California and northward in the coastal mountains are the single-flowered gentian (G. simplex), with slightly fringed flow ers, and the western blue gentian (G. calycosa), which through out the summer forms sheets of intense blue in alpine meadows from California to British Columbia and eastward to Montana.
By far the most important of the species used in medicine is G. lutea, a large handsome plant 3 or 4 ft. high, growing in open grassy places on the Alps, Apennines and Pyrenees, as well as on some of the mountainous ranges of France and Germany, extend ing as far east as Bosnia and the Danubian principalities. It has large oval strongly-ribbed leaves and dense whorls of conspicuous yellow flowers. Its use in medicine is of very ancient date. Pliny and Dioscorides mention that the plant was noticed by Gentius, a king of the Illyrians, living 180-167 B.C., from whom the name Gentiana is supposed to be derived. During the middle ages it was much employed in the cure of disease, and as an ingredient in counter-poisons. In 1S52 Hieronymus Bock (Tragus) (1498 a German priest, physician and botanist, mentions the use of the root as a means of dilating wounds.
The root, which is the part used in medicine, is tough and flexi ble, scarcely branched, and of a brownish colour and spongy tex ture. It has a pure bitter taste and faint distinctive odour. The bitter principle, known as gentianin, is a glucoside, soluble in water and alcohol. It can be decomposed into glucose and gentiopicrin by the action of dilute mineral acids. It is not precipitated by tannin or subacetate of lead. A solution of caustic potash or soda forms with gentianin a yellow solution, and the tincture of the root to which either of these alkalis has been added loses its bitterness in a few days. Gentian root also contains gentianic acid which is inert and tasteless. It forms pale yellow silky crystals, very slightly soluble in water or ether, but soluble in hot strong alcohol and in aqueous alkaline solutions. This sub stance is also called gentianin, gentisin and gentisic acid.
The root also contains 12 to 15 % of an uncrystallizable sugar called gentianose, of which fact advantage has long been taken in Switzerland and Bavaria for the production of a bitter cordial spirit called Enzianbranntwein. The use of this spirit, especially in Switzerland, has sometimes been followed by poisonous symp toms, which have been doubtfully attributed to inherent narcotic properties possessed by some species of gentian, the roots of which may have been indiscriminately collected with it ; but it is quite possible that it may be due to the contamination of the root with that of Veratrum album, a poisonous plant growing at the same altitude, and having leaves extremely similar in appearance and size to those of G. lutea.
Gentian is one of the most efficient of the class of substances which act upon the stomach so as to invigorate digestion and thereby increase the general nutrition, without exerting any direct influence upon any other portion of the body than the alimentary canal. Having a pleasant taste and being nonastringent (owing to the absence of tannic acid), it is the most widely used of all bit ter tonics. The British Pharmacopoeia contains an aqueous ex tract (dose, 2-8 grains), a compound infusion with orange and lemon peel (dose, 2 1 ounce), and a compound tincture with orange peel and cardamoms (dose i r drachm). It is used in dyspepsia, chlorosis, anaemia and various other diseases, in which the tone of the stomach and alimentary canal is deficient, and is sometimes added to purgative medicines to increase and improve their action. In veterinary medicine it is also used as a tonic, and enters into a well-known compound called diapente as a chief ingredient.