Perennial herbaceous plant that grows wild or can be cultivated. The various species are native to the Far East, but they are well acclimated to the Mediterranean regions as well. Their cultivation in Italy represents a flourishing industry.I. pallida Lam. is the best variety for extractive purposes, followed by I. germanica and I. florentina (which is cultivated mainly for ornamental purposes). Depending on the variety, the plant exhibits blue, deep blue, or whitish-blue veined flowers. It has an erect stem and radical leaves. It has large, horizontal, highly branched, and fleshy rhizomes exhibiting a pleasant and persistent odor. The fragrance of I. pallida is most persistent.
The peeled rhizomes (roots) are used after two years of aging. Commercial qualities include straight, twisted, and knotty rhizomes. Orris has a violet-like odor with a fruity undertone.
Orris concrete: Orris butter, or orris concrete, is obtained by steam distillation of dried ground rhizomes with yields ranging between 0.2 to 0.3%. Special techniques and prolonged distillation are required. It contains 13% to 17% ketones (sometimes more) calculated as irone; 83 to 86% free or partially esterified fatty acids (e.g., myristic); terpene and sesquiterpene alcohols; aldehydes; and esters. The physical-chemical constants vary, depending on the origin of the rhizomes. At room temperature, orris concrete from 1. pallida Lam. is a light yellow-brown solid mass with a violetlike fragrance; at 40 to 50℃ the product melts to a yellow to yellow-brown liquid.
Orris absolute: Obtained by alcoholic extraction of the concrete to separate the fatty acids and their esters. It may contain from 55 to 85% ketones (irone).
Orris resinoid: The resinoid is prepared by extracting the comminuted rhizomes with yields of 2.4 to 3.3% using benzene, or 1 to 2% using petroleum ether. An absolute can be prepared from the resinoid; this contains 62 to 78% ketones (irone).
The derivatives are fluid extract, concrete and absolute essence, resinoid, and the tincture (20% in 50 to 60% ethanol or 30% in 55% ethanol).