Centaurea Benedicta. Blessed Thistle.
Nat. Ord. — Asteraceae. Sex. Syst. — Syngenesia Frustranea.
Description. — Centaurea Benedicta, or Cnicus Benedictus of De Candolle, also known as Holy Thistle, is an annual, herbaceous plant, with a whitish, fibrous, branched, tapering root, with several stems, about two feet high, and which are trailing, roundish, furrowed, reddish, woolly, and branching toward the top. The lower leaves are petiolate, but the upper are sessile, alternate, and somewhat decurrent; the whole are oblong, rough, aculeate, sinuate or almost ruminate, and armed with many sharp spines ; of a green color above, and paler and reticulated beneath. The flowers are large, of a bright-yellow color, solitary at the ends of the branches, inclosed by a bracteate involucrum of ten leaves, the five exterior of which are largest. True involucrum ovoid, imbricated, smooth, woolly, each scale being terminated by pinnate spines, connected with the bracts by fine threads. Ray-florets small and sterile, those of the disk perfect, tubular, and toothed. Stamens five, downy, with linear-oblong united anthers. The style is filiform with a cleft stigma. The achenia are oblong, brown, striated, on a bristly receptacle.
History. — This is a native of the south of Europe, and naturalized in the United States. It flowers in June, when its medicinal virtues are in the greatest perfection. The leaves should be gathered while the plant is in flower, quickly dried, and kept in a dry place. They have a feeble, unpleasant odor, and an intensely bitter taste. Water or alcohol extracts their virtues. The infusion with cold water is a pleasant bitter; the decoction is nauseous and offensive to the stomach. The leaves contain volatile oil, a bitter principle, resin, a fixed oil, gum, sugar, albumen, some salts, etc. The bitter principle is supposed to be the active one of the plant, and is named Cnicin; it is crystallizable, inodorous, very bitter, neutral, hardly soluble in cold water, more so in boiling, and soluble in alcohol. It is analogous to salicin in composition, and consists of carbon, hydrogen, and oxygen. In doses of from four to eight grains it often vomits and has proved useful in intermittent fevers.
Properties and Uses. — A cold infusion is tonic ; a warm infusion diaphoretic, and if strong, emetic. Used as a tonic in loss of appetite, dyspepsia, and intermittent diseases. Dose of the powder, from ten to sixty grains ; of the infusion two fluidounces.
Off. Prep. — Infusum Centaureae.