Iridis Rhizoma. Orris Rhizome.

Related entry: Blue flag

Synonyms.—Orris; Orris Root.

Orris rhizome is obtained from Iris germanica, Linn., I. pallida, Lamarck, and I. florentina, Linn. (N.O. Irideae), all of which are cultivated in Italy. The rhizomes are dug up in the late summer, freed from the roots, growing portions, etc., then peeled, and slowly dried. When fresh they are almost odourless, the characteristic aroma developing during the slow drying and subsequent storage of the root. Several varieties of orris root are found in commerce. The best is Florentine, which is carefully peeled, pale in colour, plump, and very fragrant. Verona orris is less carefully peeled, has a yellowish colour, and is not so plump; many of the pieces have a hole at one end by which they have been suspended to dry. The dried and peeled rhizome occurs usually in pieces from 5 to 10 centimetres long and 2.5 centimetres wide. They are whitish in colour, slightly flattened, and exhibit enlargements and contractions, each enlargement representing a year's growth. One or two short branches are usually attached to the larger extremity. The under surface bears numerous conspicuous, circular root-scars, and the upper surface indistinct leaf-scars or traces of the fibrovascular bundles of these which have passed from leaf to rhizome. The root is firm and compact. The transverse section shows a comparatively narrow cortex separated by a brownish cambium line from the large stele; the latter exhibits here and there small shining crystals of calcium oxalate. The powdered drug may be recognised by the starch grains, which are mostly simple (25μ to 30μ long and 10μ to 25μ wide), oval or elliptical in outline, and with distinct branching hilum; it contains large (250μ by 30μ) prismatic crystals of calcium oxalate, thick-walled parenchymatous tissue, but no bast fibres. Mogador orris rhizome is much darker than Italian, exhibits portions of reddish cork and the remains of buds, and is much inferior to both Florentine and Verona orris. Indian orris occurs in small, unpeeled pieces, with but little aroma.

Constituents.—Orris rhizome yields by distillation with steam from 0.1 to 0.2 per cent. of a yellowish, aromatic substance, solid at ordinary temperatures, and known as oil or butter of orris. About 85 per cent. of this is myristic acid, the remaining 15 per cent. consisting of irone, methyl myristate, oleic acid, esters, etc. Irone, C₁₃H20O, is an oily liquid with a pungent odour, quite distinct from that of violets; the violet odour is, however, very perceptible when irone is dissolved in a large volume of alcohol and a little is allowed to evaporate. The drug also contains a crystalline glucoside, iridin (which must be carefully distinguished from the resinoid obtained from Iris versicolor), abundance of starch, and a little resin. Orris rhizome yields about 5 per cent. of ash.

Action and Uses.—Preparations of orris rhizome were formerly used as mild cathartics and diuretics, but the dried root is used now only for its agreeable odour. Trimmed pieces of the root are given to infants to assist dentition, and are used also to perfume the breath. The powdered rhizome is a common ingredient of dentifrices and toilet powders. The volatile otto of orris is used in perfumery.

PREPARATION.

Pulvis Violaris, B.P.C.—VIOLET POWDER.

Orris rhizome, in fine powder, 12.5; with oil of bergamot, oil of neroli, and starch, to 100.

The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.