Iris pallida

Iris pallida, the Dalmatian iris or sweet iris, is a hardy flowering perennial plant of the genus Iris, family Iridaceae. It is native to the Dalmatian coast in Croatia but widely naturalised elsewhere. It prefers rocky places in the Mediterranean and Submediterranean zone. It grows to a stem height of 50-80 cm. The fan-shaped inflorescence, produced in May or June, contains two or three flowers, which are usually pale purplish to whitish. Iris pallida flowers last longer than those of other Iris species, but take longer to develop, especially in colder climates. Some authors recognise three subspecies of Iris pallida in the broad sense as species: cengialti, from Slovenia and adjacent Italy, illyrica, from the North Dalmatian coast, and pseudopallida, from the South Dalmatian coast. The variegated cultivar 'Variegata' has gained the Royal Horticultural Society's Award of Garden Merit.

Orris root is the root of Iris germanica and Iris pallida. Iris pallida is cultivated in the Chianti region of Italy for its fragrance and medicinal properties. It is grown as a garden plant and commercially for the extraction of essential oils from its rhizome. The rhizomes of the orris species I. florentina, I. germanica and I. pallida produce one new rhizome section, called a struma, per year of growth on average. In Italy, irises were grown as an intercrop in vineyards and olive orchards, on narrow and steep plots of land for which mechanization is unsuitable. In these conditions, all work is usually performed by hand. Italy, once the hallmark of orris production, is now limited to the areas of Chianti and Pratomagno in Tuscany, where less than 30 tons is produced annually. Notable orris production also comes from Morocco, with an estimated 120 tons of I. germanica annually, from China, with about 100 tons of I. pallida, and from France, with about 40 tons of I. pallida. Orris essential oil costs several thousands of euros per kg, given the long process required to obtain it.

Irones are a group of methylionone odorants used in perfumery, derived from iris oil. Traditional aging of the rhizomes is a slow desiccation in which oxidative degradation of iridals leads to the slow accumulation of irones. Five geometrical irone isomers have been fully identified in Iris: cis-α-irone, trans-α-irone, cis-γ-irone, trans-γ-irone and β-irone. The α-, β- and γ-irones differ in the position of the double bond on the cyclohexane ring. Dextrorotatory irones are found in I. pallida, whereas levorotatory irones are found in I. germanica. In one comparison, I. pallida essential oil had 61% cis-γ-irone, 34% cis-α-irone and 5% trans-α-irone, while I. germanica essential oil had 62% cis-α-irone, 37% cis-γ-irone and 1% trans-α-irone. The main components of orris absolute are cis-γ-irone, typically 30-40%, and cis-α-irone, typically 20-30%. These two irones are considered responsible for the typical orris odor. The α-irone and γ-irone contents are accepted as the most significant criteria of the commercial quality of iris essential oil. In a study of I. pallida from Ukraine, the rhizome oil held myristic acid (56%), capric acid (14.50%), lauric acid (15.42%) and α-irone (2.85%) as dominant compounds.

The rhizomes are also used to make beads for children's teething necklaces as well as rosary beads.

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Related: Alpha Ionone · Alpha Isomethyl Ionone · Beta Ionone · Boisiris · Iris · Iris Butter · Orris Absolute