madder; a genus of the monogyne order, belonging to the tetrandra clas of plants. There are three species, of which the most remarkable is the tinctorum, or dyer's madder, so much used by the dyers and calico-printers. This hath a perennial root and annual stalk: the root is composed of many long, thick, succulent fibres, almost as large as a man's little finger; these are joined at the top in a head like asparagus, and run very deep into the ground. From the upper part, or head of the root, come out many side-roots, which extend just under the surface of the ground to a great distance, whereby it propagates very fast; for these send up a great number of shoots, which, if carefully taken off in the spring soon after they are above ground, become so many plants. These roots are of a reddish colour, somewhat transparent; and have a yellowish pith in the middle, which is tough and of a bitterish taste. From this root arise many large four-cornered jointed stalks, which, in good land, will grow five or six feet long; and, if supported, sometimes seven or eight: they are armed with short herbaceous prickles; and at each joint are placed five or six spear-shaped leaves: their upper surfaces are smooth; but their midrib on the under side is armed with rough herbaceous spines, and the leaves sit close to the branches in whorls. From the joints of the stalk come out the branches, which sustain the flowers: they are placed by pairs opposite; each pair crossing the other: these have a few small leaves toward the bottom, which are by threes, and upwards by pairs opposite: the branches are terminated by loose branching spikes of yellow flowers, which are cut into four parts resembling stars. These appear in June, and are sometimes succeeded by seeds, which seldom ripen in England. For the manner of its cultivation and preparation for the use of dyers, see the article Madder.

Madder-root is used in medicine. The virtues attributed to it, are those of a detergent and aperient; whence it has been usually ranked among the opening roots, and recommended in obstructions of the viscera, particularly of the kidneys, in coagulations of the blood from falls or bruises, in the jaundice and beginning dropsies. It is an ingredient in the icteric decoction of the Edinburgh pharmacopoeia.

It is observable, that this root taken internally, tinges the urine of a deep red colour; and in the Philosophical Transactions we have an account of its producing a like effect upon the bones of animals who had it mixed with their food: all the bones, particularly the more solid ones, were said to be changed, both externally and internally, to a deep red; but neither the fleshy or cartilaginous parts suffered any alterations: some of these bones macerated in water for many weeks together, and afterwards steeped and boiled in spirit of wine, lost none of their colour, nor communicated any tinge to the liquors. This root, therefore, was concluded to be possessed of great subtilty of parts, and its medical virtues hence to deserve inquiry. The same trials, however, made by others, have not been found to produce the same effects as those above-mentioned.—Of late the root has come into great reputation as an emmenagogue.