HORSERADISH, known botanically as Cochlearia Armora cia, a perennial plant of the family Cruciferae, having a stout cylindrical rootstock from the crown of which spring large radical leaves on long stalks, 4 to 6 in. broad, and about a foot in length with a deeply crenate margin, and coarsely veined ; the stem leaves are short-stalked or sessile, elongated and tapering to their attachment, the lower ones often deeply toothed. The flowers, which appear in May and June, area in. in width, in flat-topped panicles, with purplish sepals and white petals ; the fruit is a small silicula, which does not ripen in the climate of England. The horseradish is indigenous to eastern Europe. Into western Europe and Great Britain, where it is to be met with on waste ground, it was probably introduced. It has extensively escaped from cultivation in North America.
The root, the armoraciae radix of pharmacy, is i to 2 in. or more in diameter, and commonly 1 ft., sometimes 3 ft. in length; the upper part is enlarged into a crown, which is annulated with the scars of fallen leaves ; and from the numerous irregular lateral branches are produced vertical stolons, and also adventitious buds, which latter render the plant very difficult of extirpation. From the root of Aconite (q.v.), which has occasionally been mistaken for it, horseradish root differs in being more or less cylindrical from a little below the crown, and in its pale yellowish (or brown ish) white hue externally, acrid and penetrating odour when scraped or bruised, and pungent and either sweetish or bitter taste. Under the influence of a ferment which it contains, the fresh root yields on distillation with water about .o5% of a volatile oil, butyl sulphocyanide, In common with other species of Cochlearia, the horseradish was formerly in high repute as an antiscorbutic. The root was, as well as the leaves, taken with food by the Germans in the middle ages, whence the old French name for it, moutarde des Allemands.