Gentian, in botany: A genus of the digynia order, belonging to the pentandra clas of plants; and in the natural method ranking under the 20th order, Rotae. The corolla is monopetalous; the capsule bivalved and unilocular; there are two longitudinal receptacles. The most remarkable species are the following:

1. The lutea, or common gentian of the shops. It is a native of the mountainous parts of Germany; from whence the roots, the only part used in medicine, are brought to this country. These have a yellowish-brown colour, and a very bitter taste. The lower leaves are of an oblong oval shape, a little pointed at the end, stiff, of a yellowish green, and have five large veins on the back of each. The stalk rises four or five feet high, garnished with leaves growing by pairs at each joint, almost embracing the stalk at their base. They are of the same form with the lower, but diminish gradually in their size to the top. The flowers come out in whorls at the joints on the upper part of the stalks, standing on short foot-stalks, whose origin is in the wings of the leaves. They are of a pale yellow colour.—The roots of this plant are very frequently used in medicine as stomachic bitters. In taste they are less exceptionable than most of the substances of this class. Infusions of gentian-root flavoured with orange-peel, are sufficiently grateful. Some years ago a poisonous root was discovered among the gentian brought to London; the use of which occasioned violent disorders, and in some cases death. This root is easily distinguished from the gentian, by its being internally of a white colour, and void of bitterness.

2. The centaureum, or lesser centaury of the shops, is a native of many parts of Britain. It grows on dry pastures; and its height is commonly proportioned to the goodness of the soil, as in rich soils it will grow to the height of a foot, but in poor ones not above three or four inches. It is an annual plant, with upright branching stalks, garnished with small leaves, placed by pairs. The flowers grow in form of an umbel at the top of the stalk, and are of a bright purple colour. They come out in July, and the seed ripens in autumn. The plant cannot be cultivated in gardens. The tops are an useful aperient bitter, in which view they are often used in the present practice of medicine.