In the centre of the blade, some of the rhizomatous irises have a "beard", a row of fuzzy hairs at the base of each falls petal which gives pollinators a landing place and guides them to the nectar.

Some smaller iris species have all six lobes pointing straight outwards, but generally limb and standards differ markedly in appearance.

Like some older sources, Rodionenko moved some of the bulbous subgenera (Xiphium, Scorpiris and Hermodactyloides) into separate genera (Xiphion, Juno and Iridodictyum respectively), but this has not been accepted by later writers such as Mathew (1989), although the latter kept Hermodactylus as a distinct genus, to include Hermodactylus tuberosus, now returned to Hermodactyloides as Iris tuberosa.

[15] In general, modern classifications usually recognise six subgenera, of which five are restricted to the Old World; the sixth (subgenus Limniris) has a Holarctic distribution.

Although diverse in ecology, Iris is predominantly found in dry, semi-desert, or colder rocky mountainous areas.

can tolerate damp (bogs) or dry sites (meadows),[19] and Iris foetidissima can be found in woodland, hedge banks and scrub areas.

[21][22] Wylie et al., 2014,[22] made the first identification of Narcissus mosaic virus infecting this garden plant genus, and the first record in Australia.

[26] The earliest to bloom are species like I. reticulata and I. reichenbachii, which flower as early as February and March in the Northern Hemisphere, followed by the dwarf forms of I. pumila and others.

The "beard", short hairs arranged to look like a long furry caterpillar, is found toward the back of the lower petals and its purpose is to guide pollinating insects toward the reproductive parts of the plant.

A truly red bearded iris, like a truly blue rose, remains an unattained goal despite frequent hybridizing and selection.

[32] There are species and selections, most notably based on the beardless rhizomatous Copper iris (I. fulva), which have a relatively pure red color.

[33] Pelargonidin-derived anthocyanins would lend the sought-after blue-based colors but these genera are metabolically disinclined to produce pelargonidin.

[33] The bias in irises towards delphinidin-anthocyanins is so pronounced that they have served as the gene donors for transgenic attempts at the aforementioned blue roses.

Species of section Oncocyclus are generally strict endemics, typically occurring in a small number of scattered, disjunct populations, whose geographical isolation is enhanced by their pollination strategy and myrmecochory seed dispersal.

[45][46] Compared with other irises, the cushion varieties are scantily furnished with narrow sickle-shaped leaves and the flowers are usually borne singly on the stalks; they are often very dark and in some almost blackish.

They should not be disturbed in the autumn, and after the leaves have withered the roots should be protected from heavy rains until growth starts again naturally.

They are best planted in September or October in warm sunny positions, the rhizomes being lifted the following July after the leaves have withered.

I. unguicularis is a late-winter-flowering species from Algeria, with sky-blue flowers with a yellow streak in the centre of each petal, produced from Winter to Spring.

Reticulate irises with their characteristic bulbs, including the yellow I. danfordiae, and the various blue-purple I. histrioides and I. reticulata, flower as early as February and March.

Many of the smaller species of bulbous iris, being liable to perish from excess of moisture, should have a well-drained bed of good but porous soil made up for them, in some sunny spot, and in winter should be protected by a covering of half-decayed leaves or fresh coco-fiber.

In this time, the fats and oils inside the roots undergo degradation and oxidation, which produces many fragrant compounds that are valuable in perfumery.

The aged rhizomes are steam-distilled which produces a thick oily compound, known in the perfume industry as "iris butter" or orris oil.

Larger blue flag (I. versicolor) and other species often grown in gardens and widely hybridized contain elevated amounts of the toxic glycoside iridin.

This highly aggressive grower is now considered a noxious weed and prohibited in some states of the US where it is found clogging natural waterways.

[53] The American artist Joseph Mason – a friend of John James Audubon – painted a precise image of what was then known as the Louisiana flag or copper iris (Iris fulva), to which Audubon subsequently added two Northern paraula birds (Parula americana) for inclusion as Plate 15 in his Birds of America.

The artist Philip Hermogenes Calderon painted an iris in his 1856 work Broken Vows; he followed the principles of the Pre-Raphaelite Brotherhood.

It also conveys images of lost love and silent grief, for young girls were led into the afterlife by the goddess Iris.

[54] Contemporary artist George Gessert, who introduced the cultivation of flowers as an art form, has specialised in breeding irises.

[69][70] In the Homeric Hymn to Demeter, the goddess Persephone and her companion nymphs (the Oceanids along with Artemis and Athena) were gathering flowers such as rose, crocus, violet, iris (also called 'agallis' or ἀγαλλίς (in Greek script),[71] lily, larkspur,[72] and hyacinth[73] in a springtime meadow before she was abducted by the god Hades.

[79][30][80] French King Clovis I (466–511), when he converted to Christianity, changed his symbol on his banner from three toads to irises (the Virgin's flower).