401. IMPERATORIA.—MASTERWORT. The root of Imperato'ria ostru'thium Linné. Habitat: Southern Europe. A conical root with a dark brownish-gray, annulated and tuberculated bark, inclosing a whitish wood-circle and a resin-dotted central pith; odor angelica-like; taste pungent and bitter. It is a stimulant aromatic, but is rarely used in this country.