This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
Orris rhizome, or root as the drug is commonly termed, is derived from three species of Iris (N.O. Irideoe), all of which are cultivated for that purpose, viz.: -
Iris germanica, Linne, a handsome plant with dark blue or purplish blue flowers, distributed over central and southern Europe, extending to Africa and India, and a common garden plant in England. It is cultivated in Italy, especially in the neighbourhood of Florence and Verona, and also in Morocco.
Iris pallida, Lamarck, with pale bluish flowers, a native of the eastern Mediterranean countries; it is also cultivated in Italy, and yields with I. germanica the bulk of the drug.
Iris florentina, Linne, with large white flowers, also a native of the eastern Mediterranean region, and cultivated in Italy, but not so abundantly as the other two.
The rhizomes of all three species so closely resemble one another that there are no definite means of distinguishing them. They are dug up in the late summer when two or three years old, trimmed and peeled; they are dried in the sun on a kind of matting made of bamboo rods for about 5 days; they are then spread on a cool, dry, tiled floor for 8 days and finally sorted by hand. During the slow drying the rhizomes, which in the fresh state are almost inodorous and have an acrid taste, acquire an agreeable fragrance and lose their acridity.
Orris rhizome occurs usually in pieces from 5 to 10 cm. long and 2 to 3 cm. thick, of a dull white colour. They are often dorsi-ventrally flattened and contracted at intervals or bear one or two short lateral branches at the apex. Each of the enlargements corresponds to a year's growth of the rhizome; the branches are developed from buds after the rhizome has flowered, which may not occur for three or four years.
The under surface is marked with the small dark circular scars of roots, and on the upper surface traces of the leaves, or at least of the fibro-vascular bundles that passed into them, can be discerned, the drug showing distinct evidence of having been peeled. It is hard, heavy, and compact, and breaks with a short fracture, the interior being yellowish and horny.
The transverse section exhibits a large stele containing scattered darker bundles and a comparatively narrow cortex.
The drug has an agreeable aromatic odour and a slightly bitter taste.
The student should particularly observe
(a) The contractions of the rhizome,
(b) The scars of leaves upon the upper and of roots on the under surface,
(c) The characters of the transverse section,
(d) The characteristic odour.
By distillation with steam, orris rhizome yields about 0.l or 0.2 per cent. of a yellowish, buttery, aromatic substance, commonly called oil or butter of orris; this consists principally (about 85 per cent.) of myristic acid together with irone, an oily liquid with a powerful odour of violets. Irone is the only aromatic constituent of the rhizome. The drug also contains a crystalline glucoside, iridin, which must be carefully distinguished from the brown, resinous, eclectic remedy of the same name; the latter is obtained from the rhizome of Iris versicolor, Linne.
Orris rhizome is used as a perfume, dentifrice, etc, although formerly medicinal qualities were attributed to it.
The chief commercial varieties of orris root are the Florentine, Veronese, and Mogadore. A very inferior quality, of small size, dark colour, and little fragrance, is occasionally imported from Bombay.
Fig. 205. - Orris rhizome. Rhizome of Iris germanica. a, constrictions indicating winter growth; b, b, young branches; c, scar left by previous year's flowering shoot. (Tschirch, after Hartwich).
Florentine orris root is usually nearly white in colour, carefully peeled, plump, and very fragrant.
Veronese orris root closely resembles the Florentine, but generally has a yellower colour, is rather less carefully peeled, often more wrinkled and more elongated; most of the pieces are pierced with a small hole at one end by which they were strung during the drying.
Mogadore orris root is altogether inferior to both the foregoing varieties. It is in smaller, flatter, and more shrunken pieces, which often bear at their apices the shrivelled remains of numerous concentrically arranged leaves. Patches of reddish cork are left attached to the drug, which is of darker colour and inferior fragrance.
Iris versicolor, Linne. The rhizome is narrow, dark brown, longitudinally wrinkled, and purplish internally; the taste is pungent and acrid. It is the source of the ' iridin ' of commerce.
Fig. 206. - Orris rhizome. Transverse sections. o, cortex; v, endodermis; 6, stele. Natural size. (Berg).