Iris florentina, also known as Iris albicans, cemetery iris, white cemetery iris, or the white flag iris, is a species of iris which was planted on graves in Muslim regions and grows in many countries throughout the Middle East and northern Africa. It was later introduced to Spain, and then other European countries.

The identity of the plant first described by Carl Linnaeus as Iris florentina remains unclear, . In horticulture, it has been treated as a white-flowered variant of Iris × germanica, under names such as Iris germanica nothovar. florentina, Iris × germanica var. florentina and Iris × germanica 'Florentina'. Iris florentina has also been treated as the correct name for the true species also known as Iris albicans Lange.

It is cultivated as an ornamental plant in temperate regions almost worldwide and is a rhizomatous perennial from southern Europe, mainly Italy (including the city of Florence) and France. It has a thick violet-scented rhizome, sword-like green or grey-green semi-evergreen leaves, a tall branched stem, and many flowers that are white and tinged or flushed with blue, pale blue, or lavender in spring or summer, and a white and yellow beard. It is also grown to produce orris-root, a scented substance used in perfumes, soaps, tooth cleanser, and clothes washing powder. Medicinally it was used as an expectorant and decongestant. It is made from the rhizomes of Iris florentina, Iris germanica and Iris pallida. The flower is commonly attributed with the fleur-de-lis.

Description

Iris florentina has a thick or stout rhizome, which is short, fleshy, horizontal, and has a strong violet scent.Ruth D. Wrensch Christopher Brickell (Editor)

The rhizomes spread across the surface of the soil, to form clumps of plants. This habit can often create a dense network of fibrous roots that can crowd out other plants.Neil Fletcher

It has basal (rising up from the rhizome),John Lust ensiform (sword-shaped),John Sims Caledonian Horticultural Society, Edinburgh Stefan Buczacki light green, pale green, or grey-green leaves. They are semi-evergreen, or evergreen (in mild winters).Walter Stager The leaves can grow up to between long, and between wide.Richard Lynch and Henry Ewbank They are shorter than the stem.

It has a straight, stem or peduncle, that can grow up to between tall.William Robinson It grows to 30–60 cm tall. The leaves are grey-green, and broadly sword-shaped. It may reach up to after about 3 years. Although it may reach , (in ideal conditions). The stems have 2–4 branches. The branches reduce in size as you go up the stem, starting from the middle. The branches can be long.

The stem has 1–2, (scarious) membranous or sub-scarious, spathes (leaves of the flower bud).British Iris Society (1997) At flowering time, the spathes become brown and papery,James Cullen, Sabina G. Knees, H. Suzanne Cubey (Editors) or fully scarious. They can be up to long. 1.5-2 in long The lower spathes are green and leaf-like.

It has a short pedicel (or flower stalk), and green perianth tube, that is 3.2 cm long, it is covered normally by the spathes.

The stem (and the many branches) hold between 4 and 7 flowers. at terminal ends. Sometimes in pairs. The fragrant flowers, smell of violets, appear in spring, or early summer, or mid-summer, between late April and May, or between March and May.

The large flowers, are up to in diameter (or across). They come in white,Thomas Gaskell Tuti (Editor) (sometimes described as 'dead white,) or greyish white, or bluish white, or very pale lavender. They are slightly tinged, or flushed with blue, or pale blue, or lavender. They are especially tinted when in bud.

Like other irises, it has 2 pairs of petals, 3 large sepals (outer petals), known as the 'falls' and 3 inner, smaller petals (or tepals), known as the 'standards'. The deflexed, or drooping falls, are obovate, or cuneate (wedge) shaped. They are long and wide. There is some greenish-yellow veining on the haft, (section of the petal near the stem), and in the centre of the falls, there is a narrow fillet of white cilias (called a beard) with deep yellow tips, bright yellow, or orange yellow. The standards are erect, oboval, and narrower than the falls. The hafts of the standards, have a small white beard.

It has style branches, that are toothed and 3.8 cm long, with a deltoid crests. It has an oblong shaped and pearl coloured stigma.

After the iris has flowered, between July and August, it produces a fusiform (spindle shaped), trigonal, or oblong seed capsule. It is longer than the seed capsule of Iris germanica. The capsule is loculicidal (has chambers), with 3 cells, that hold dark brown, or brown seeds. The seeds are normally lined up like rolls of coins.

Biochemistry In 1973, a chemical study was carried out on Iris florentina, it found isoflavone glycosides.

A 1973 study isolated a xanthone (irisxanthone) from Iris florentina, which was identified as the tetraoxygenated xanthone glycoside 2-C-β-D-glucopyranosyl-5-methoxy-1,3,6-trihydroxyxanthone

In 2014, a study was carried out on the essential oil of Iris florentina. It found several compounds including decanoic acid, ethanon, α-iron, trans-2,6-γ-iron, lauric acid, myristic acid, palmitic acid, 9,12 oktadecadienoic acid and hexanedioic acid bis ester.

In 2015, a study was carried out on the antioxidant and anticholinesterase potential of the iris.

Karyology As most irises are diploid, having two sets of chromosomes, this can be used to identify hybrids and classification of groupings. Iris florentina has a count of 2n=44, meaning it is a tetraploid.

Taxonomy

It has the common names of 'Florentine Iris', 'Florentine Flag' (in the US), 'Glaive lily', 'White German Iris', and 'White Flower De Luce',

It is sometimes known as orris root, which also comes from the rhizomes of Iris germanica and Iris pallida.

The French call it commonly as 'la flambe blanche' (the white torch of the garden).Jennifer Helvey

It is known in Malta as 'Fjurduliz abjad', in Danish as 'violrod', in France as 'Iris de florence', in German as 'Florentinische Schwertlilie', in Spanish (and Portuguese) as 'lirio blanco' or 'lirio de Florencia'.John H. Wiersema and Blanca León

The Latin specific epithet florentina refers to a 'Latinised' word meaning ‘from Florence’.D. Gledhill

It was first collected in Italy, and then introduced to N. Europe in about 1500. It has been cultivated for centuries in Europe.

It was first published and described by Carl Linnaeus, in Systema Naturae Edition 10, Issue2 on page863 on 7 June 1759, as Iris florentina. It was thought to be similar to Iris germanica, but with white flowers.

In 1796, Iris officinalis Salisb. was published by Salisb in Prodr. Stirp. Chap. Allerton Vol.43. But this was later classed as Iris florentina.

In 1910, William Rickatson Dykes in The Gardeners' Chronicle of September 17, 1910, felt that Iris florentina was not a wild species but had hybrid origin, or form of Iris germanica.

In his book, 'The Iris' in 1981, Brian Mathew, re-classified the iris as Iris germanica 'Florentina'.

This later became Iris germanica nothovar. florentina.

It was verified by United States Department of Agriculture and the Agricultural Research Service on 19 October 1994, then updated on 12 September 2005, as Iris germanica L. nothovar. florentina Dykes.

It is listed in the Encyclopedia of Life as Iris germanica var. florentina.

Iris florentina is an accepted name by the RHS, it was given the Award of Garden Merit in 1994.

Distribution and habitat It is native to central, and southern Europe.

Range It is found in Italy, (including Tuscany,) France, and the Mediterranean islands, (including Malta).

Iris florentina has been cultivated since ancient times and may be the oldest iris in cultivation. Collected by Lange in 1860, it has been in cultivation since at least 1400 BC. Originating from Yemen and Saudi Arabia, it appears in a wall painting of the Botanical Garden of Tuthmosis III in the Temple of Amun at Karnak in ancient Thebes dated around 1426 BC.

Botanist Desfontaines found it in Algiers, where it is grown with Iris germanica near graves.

It has been naturalised in many other countries, from the Mediterranean, (including west Africa and southern Spain,) to India, and Iran. In Russia, it grows in the south of western Siberia. Outside of Russia, it is found in Kazakhstan, Mongolia and China.

In many regions of the world, especially in Italy, it is cultivated for commercial use.

Habitat It grows on sunny mountain slopes, on steppes, sandy or rocky dry slopes.

It naturalises along roadsides, field margins, olive groves, abandoned vineyards and other cultivated sites.

Conservation All the stations in the other countries where it has become naturalized for centuries, it is gone, or they are declining. Not protected by law and not listed in the flora section of the National Red Data book (1989)

Cultivation It is hardy, to between USDA Zone 3 and Zone 9, or between 5 and 8. It is also hardy to Zone H2 (in Europe), between −15 and -20oC (5 to −4oF). It has been tested for hardiness in Russia, in the botanical gardens of; Barnaul, Novosibirsk, St. Petersburg and Ufa. In the winter, it requires protection from moisture (in Russia). It can be cultivated well throughout Europe and N America, except in the warm moist climates of Florida and Gulf Coast.

Iris florentina is included in the Tasmania Fire Service's list of low flammability plants, indicating that it is suitable for growing within a building protection zone.

It prefers to grow in moist, well drained soils, in loam. It can tolerate sandy soils, or any common garden soil. It also tolerates most soil pH levels of, and will tolerate very alkali or acid soils.

It prefers a situation in full sun, to light shade.

It will suffer from rhizome viruses in waterlogged soil.

It can be grown in mixed flower borders, rock gardens, and beside the edges of shrubberies. As well as being naturalized in the garden.William Robinson It can be a cut flower for displays.

It is deer and rabbit resistant, but can suffer from leaf spot, Iris borer, thrips, slug and snails. Aphids Aphis newtoni and Dysaphis tulipae can also be found on the plant.R. L. Blackman, Victor F. Eastop

The irises are planted shallow, leaving the tops of the rhizomes exposed, to the sun. They are not mulched, as this could cause rotting to the rhizomes. They can be fertilized in early spring, and again in late summer, with a general fertilizer or bone meal. The foliage can be cut back in the autumn, after the flowers have faded.

Propagation Iris florentina can only be propagated by division, of the rhizomes, after flowering, up to six weeks after flowering, and in the autumn.

They should be divided every 3 to 4 years, when large clumps.

The old woody-like centre, should be removed, along with any damaged sections. The rhizomes are then left exposed, to allow the cuts to callus, then the foliage is trimmed, (to reduce water loss). Then the new rhizome sections can be re-planted, in new situations and at a shallow depth.

Hybrids and cultivars It has a few cultivars including; 'Alba', 'Blue Zua', 'Bluzugraf', 'Elizabeth Huntington', 'Elsie Crouch Diltz', 'Firmament', 'Florentina purpurea', 'Gambetta', 'Janet Barnes', 'New Orleans' (which has light grey flowers), 'Queen Emma', 'Silver King', and 'Zua'.

There are a few crosses: 'Altar Candles', 'Tan Crown', 'Vendor'.

Toxicity

Like many other irises, most parts of the plant are poisonous (rhizome and leaves) and, if ingested, can cause stomach pains and vomiting. Also, handling the plant may cause a skin irritation or an allergic reaction.David G Spoerke and Susan C. Smolinske

It was noted by G.R Winter (in 1948, J Periodont 19:108) that allergic manifestations can be caused by the use of a dentifrice (teeth cleaner) containing orris root powder.D. Jesse Wagstaff

Uses