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In his 1936 paper The use of numerous measures in taxonomic issues, Ronald Fisher utilised the Iris flower data set, which included three Iris varieties, as an illustration of linear discriminant analysis.
Systematic position
Kingdom-Plantae
Order-Asparagales
Family-Iridaceae
Tribe-Irideae
Genus-Iris Tourn. ex L.
Description
Irises are perennial plants that can grow from bulbs in drier regions or from creeping rhizomes (rhizomatous irises) (bulbous irises). They feature tall, erect flowering stems that might be hollow or solid, flattened or circular in cross section, branching, simple, or all of the above. The rhizomatous species often have 3–10 sword-shaped leaves at the base that develop in large bunches. Additionally, the 2–10 narrow leaves of the bulbous species develop from the bulb. One or more symmetrical six-lobed blooms are present in the inflorescences, which have a fan-like structure. These develop on a peduncle or pedicel. The three sepals are called to as "falls," because they typically spread out or droop downward.
They can be ornamented with veining, lines, or dots as they spread out from their small base (the "claw" or "haft") into a broader extended part ("limb" or "blade"). Some of the rhizomatous irises feature a "beard" in the centre of the blade, which is a row of furry hairs at the base of each fall petal that serves as a landing spot for pollinators and directs them to the nectar.
The three, occasionally shrunken, petals are erect and partially hidden by the sepal bases. They go under the name "standards." All six lobes point straight outward in certain tiny iris species, although usually speaking, the standards and limbs look very different from one another. They form a floral tube at their base, which is located above the ovary (known as an epigynous or inferior ovary). The three styles split into petaloid branches as they approach the apex; this is important for pollination. The relationship between flowering plants and pollinating insects is illustrated by the iris flower, which is of interest.A flying insect can land on the flower thanks to its shape and the placement of its pollen-receiving and stigmatic surfaces on the outer petals. When probing for nectar, the insect will first come into contact with the perianth before moving on to the three stigmatic stamens that are carried on an ovary with three carpels. The insect will only come into contact with the pollen-covered surface of the inner whorled underside of the stamens after passing the stigma; when backing out of the flower, it will only come into contact with the non-receptive lower face of the stigma. This is because the shelf-like transverse projection on the inner whorled underside of the stamens is beneath the overarching style arm below the stigma.
The iris fruit is a capsule that splits into three sections to release a large number of seeds. Some species' seeds have an aril on them. Like the light brown seeds of the Iris stolonifera, which contain a thick white aril.
Taxonomy
According to some sources, the name alludes to the several species' vast range of bloom hues.
With up to 300 species, many of which are natural hybrids, Iris is the largest genus in the Iridaceae family. As of 2022, 310 recognised species of this genus are listed in Plants of the World Online. They have been split by modern classifications, beginning with Dykes (1913).The principal divisions were referred to as sections by Dykes. In general, other authors have referred to them as subgenera while largely maintaining Dykes' categories, using six subgenera further divided into twelve sections, as in Lawrence (1953) and Rodionenko (1987). These were subsequently classified into sixteen series under the sectional name Limneris (subgenus Limneris). Rodionenko, like some earlier sources, split up some of the bulbous subgenera (Xiphium, Scorpiris, and Hermodactyloides, respectively) into separate genera (Xiphion, Juno, and Iridodictyum, respectively), but this was rejected by later authors like Mathew (1989), who kept Hermodactylus as a separate genus and included Hermodactylus tuberosus, which has since been returned to Hermodactyloid.In order to account for the presence (Hexapogon) or lack (Iris) of arils on the seeds, referred to as arilate or nonarilate, Rodionenko also reduced the number of sections in subgenus Iris from six to two. Hexapogon should not contain all arilate species, according to Taylor (1976).
Six subgenera are typically recognised by present classifications; five of them are only found in the Old World, and the sixth, the subgenus Limniris, has a distribution that extends into the Holarctic. Sections are further classified into the two biggest subgenera. Bearded irises (also known as pogon irises), Psammiris, Oncocyclus, Regelia, Hexapogon, and Pseudoregelia are the six parts that make up the iris subgenus. Lophiris (also known as "Evansias" or "crested iris") and Limniris, which was further separated into 16 series, are the two divisions of the iris subgroup Limniris.
Evolution
To describe the process of interspecific hybridization followed by backcrossing to the parentals that is typical in this species, the term introgressive hybridization was initially developed.
Distribution
Almost all species can be found in the temperate regions of the Northern Hemisphere, which range from Europe through Asia and North America. Despite having a broad ecosystem, iris is most frequently found in arid, semi-arid, or chilly rocky mountainous regions. Grassy slopes, meadows, woodlands, bogs, and riverbanks are examples of other ecosystems. Iris foetidissima can be found in woodland, hedge banks, and scrub areas, and Iris setosa Pall. can tolerate damp or dry sites.
Cultivation
It is frequently grown as a beautiful plant in yards and botanical gardens.
Taxonomy classification differs from categorization for garden horticulture. Bulb iris and rhizome iris, also referred to as rhizomatous iris, are the two types of garden irises. Due of their different geographic origins and considerable genetic variability, iris require a wide range of growing conditions.
The dwarf forms of I. pumila flower as early as February and March in the Northern Hemisphere, followed by most of the tall bearded varieties, including the German iris and its variety florentina, sweet iris, Hungarian iris, and lemon-yellow iris. Iris grow well in most any garden soil types as long as they are well-drained (I. flavescens).The British Iris Society promotes irises in the United Kingdom.Dwarf, tall, and aril bearded iris are the different types. The hybrid iris and its several variants are the type of garden iris that are most frequently found in Europe.The lower petals' "beard," which consists of small hairs arranged to resemble a long, furry caterpillar, is there to direct pollinating insects towards the plant's reproductive organs. Bearded irises are now twice as enormous as they were a century ago thanks to breeding efforts that have made them produce far larger blooms than they previously did.
Bearded iris are popular in gardens because they are simple to grow and spread. Garden centres typically only have a modest selection at the right times of the year, while specialised suppliers have access to thousands of cultivars.The rhizome should be visible on the soil's surface and facing the sun when they are planted bare root in a sunny, open location in the late summer.Every two to three years, in the summer, when the clumps get crowded, they should be separated.Despite continuous hybridising and selection, a fully red bearded iris, like a brilliantly blue rose, remains an unattainable aim. There are varieties and species with a comparatively pure red hue, most notably those based on the beardless rhizomatous Copper iris. The vast majority of bearded iris are in the purple and blue colour range of the colour spectrum, although there are also breeds of yellow, pink, orange, and white iris. However, incorporating this colour into a modern bearded iris breed has proven to be very difficult. Irises, like many genera that are linked to them, lack red-based colours since their anthocyanins are produced from delphinidin. Anthocyanins generated from pelargonidin would contribute the desired blue-based hues, but these genera lack the metabolic capacity to manufacture pelargonidin.It is likely also true here that dihydroflavonol 4-reductases do not specifically catalyse the conversion of dihydrokaempferol to the precursor leucopelargonidin. Flavonoid 3'-hydroxylase, which suppresses the synthesis of pelargonidin in Chrysanthemum, is the source of the other metabolic challenge. The delphinidin-anthocyanin preference in irises is so strong that transgenic attempts to produce the aforementioned blue roses have used them as gene donors.
Uses
The rhizomes of the German iris and sweet iris are traded as orris root and used in perfume and medicine, despite being more common in ancient times than they are now. The dried rhizomes are frequently fed whole to babies to help them through teething. Gin companies like Bombay Sapphire and Magellan Gin employ orris root and occasionally iris flowers to add flavour and colour. Orris roots are created by extracting, drying, and ageing iris rhizomes for up to five years. The lipids and oils found inside the roots are broken down and oxidised during this time, producing a number of fragrant compounds that can be used in perfumery. It is thought that the fragrance is violet-like.The mature rhizomes are steam-distilled to create "iris butter," also known as orris oil, which is a thick, oily substance used in perfumery.Terpenes and organic acids like ascorbic acid, myristic acid, tridecylenic acid, and undecylenic acid are also present in significant concentrations in iris rhizomes. Some iris rhizomes are poisonous. Larger blue flags and other species that are frequently cultivated in gardens and extensively hybridised have higher concentrations of the hazardous glycoside iridin. Although these rhizomes can induce skin irritation, nausea, vomiting, and diarrhoea, most poisonings do not result in death. Irises should only be used medically while under a doctor's supervision.
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