GENTIAN, botanically Gentiana, a large and typical genus of herbaceous plants forming the type of the natural order Gentianacece. The genus comprises about 180 species, —most of them perennial plants growing in hilly or mountainous districts, chiefly in the northern hemisphere, some of the blue-flowered species ascending to a height of 16,000 feet in the Himalaya mountains. The leaves are opposite, entire, and smooth, and often strongly ribbed. The flowers are furnished with a persistent calyx and corolla, which is usually 4- or 5-parted, but occasionally 10-parted; 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 numerous 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 a few species occur in Britain. G. Amarella and G. cam-pestris are small annual species growing on chalky or calcareous hills, and bear, in autumn, somewhat 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. gerinanica, "Willd., has larger flowers of a more blue 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 inches. It has linear leaves, and a bright blue corolla 1^ inches long, marked externally with five greenish bands, is without hairs in its throat, and is found in perfection about the end of August. 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 in tolerable abundance. 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 occurs only on a few of the loftiest Scotch 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 the splendid blue colour of masses of gentian in flower is a sight which, when once seen, can never be forgotten. For ornamental purposes several species are cultivated. The great difficulty of growing them suc-cessfully renders them, however, less common than would otherwise be the case ; although very hardy when once established, they are very impatient of removal, and rarely flower well until the third year after planting. Of the ornamental species found in British gardens some of the prettiest are G. acaulis, G. verna, G. pyrenaica, G. bavarica, G. septemfida, and G. gelida. Perhaps the handsomest and most easily grown is the first named, often called Gentianella, which produces its large intensely blue flowers early in the spring.

All the species of the genus are remarkable for possessing an intense but pure bitter taste and tonic properties. About forty species are used in medicine in different parts of the world. The name of felwort given to 0. Amarella, but occasionally applied to the whole genus, is stated by Dr Prior to be given in allusion to these properties—-fel meaning gall, and wort a plant. In the same way the Chinese call the G. asclepiadea, and the Japanese the G. Buergeri, " dragon's gall plants," in common with several other very bitter plants whose roots they use in medicine. G. campestris is sometimes in Sweden and other northern countries a substitue for hops.

By far the most important of the species used in medicine is the G. lutea, a large handsome plant 3 or 4 feet 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, extending 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 1552 Tragus mentions the use of the root as a means of dilating wounds.

The root, which is the part used in medicine, is tough and flexible, scarcely branched, and of a brownish colour and spongy texture. It has a pure bitter taste and faint distinctive odour. On account of its porous nature it has been used in modern surgery, as in the time of Tragus, as a substitute for sponge tents. The root has been several times analysed with varying results, but Kromayer in 1862 first obtained the bitter principle in a state of purity. This substance, to which the bitterness of the root is due, he called gentiopicrin (C.20H30O12). It is a neutral glucoside, crystallizing in colourless needles, and is contained in the fresh root in the proportion of about yoth per cent., but has not been obtained in a crystalline state from the dried root. It is soluble in water and spirit of wine, but it does not dissolve in ether. It is easily decomposed, dilute mineral acids splitting it up into glucose and gentiogenin, the latter being an amorphous yellowish-brown neutral substance. It is not precipitated by tannin or subacetate of lead. A solution of caustic potash or soda forms with gentiopicrin a yellow solution, and the tincture of the root to which either of these alkalies has been added loses its bitterness in a few days. Gentian root also contains gentianic acid (C14H10O6), 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 substance, which is also called gentianin, gentisin, and gentisic acid, has been shown by Ville to partake of the nature of tannin, giving the reactions of that substance with ferric chloride, gelatin, and albumen. On this account he proposes to change the name to gentiano-tannic acid.

The root also contains 12 to 15 per cent, of anuncrystal-lizable sugar, of which fact advantage has long been taken in Switzerland and Bavaria, for the production of a bitter cordial spirit called Emianbranntwein. The use of this spirit, especially in Switzerland, has sometimes been followed by poisonous symptoms, which have been doubtfully attri-buted to inherent narcotic properties possessed by some species of gentian, the roots of which may have been indis-criminately 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 considered by therapeutists to be one of the most efficient of the simple bitter tonics, that is, of that 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. 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.

See Sowerby, English Botany, 3d edit., vol. vi. p. 74-81; Hemsley, Handbook of Hardy Trees, Shrubs, and Herbaceous Plants, p. 303; Journal of Botany, 1864, p. 65 ; 1872, p. 166 ; 1878, p. 265; Pharmacographia, p. 389; Pharmaceutical Journal (1), vol. xii. p. 371; (3) vol. iii. p. 42; (3) vol. vi. p. 90; (3) vol. viii. p. 182; "Wood and Bache, United States Dispensatory, 14th edit., p. 438; Porter Smith, Chinese Materia Medica, p. 102. (E. M. H.)