Iridaceae (/ɪrɪˈdeɪsiˌaɪ,-siːˌiː/) is a family of plants in orderAsparagales, taking its name from theirises. It has a nearly global distribution, with 69 accepted genera with a total of about 2500 species.[2][3][4] It includes a number of economically important cultivated plants, such as species ofFreesia,Gladiolus, andCrocus, as well as the cropsaffron.
Members of this family areperennial plants, with abulb,corm orrhizome. The plants grow erect, and have leaves that are generally grass-like, with a sharp central fold. Some examples of members of this family are theblue flag andyellow flag.
The family name comes from the genusIris, the family's largest and best-known genus in Europe. This genus dates from 1753, when it was coined by Swedish botanist,Carl Linnaeus. Its name derives from the Greek goddess, Iris, who carried messages fromOlympus to earth along a rainbow, whose colors were seen by Linnaeus in the multi-hued petals of many of the species.
SubfamilyIsophysidoideae ismonotypic, only containingIsophysis from Tasmania.[5] It is the only member of the family with a superior ovary, and it grows a solitary star-like, yellow to brownish flower.[7] It is also sister to all other extant taxa of Iridaceae, diverging 66mya.[5]
SubfamilyNivenioideae contained six genera from South Africa, Australia and Madagascar, including the core genera and only true shrubs in the family (Klattia,Nivenia andWitsenia).[7] Upon phylogenetic analysis, subfamily Crocoideae is always found nested within Nivenioideae, leading to it not being amonophyletic taxon.[5] A revised description of these groups led to the description ofAristea,Geosiris, andPatersonia each as separate subfamilies, retaining a core, monophyletic Nivenioideae.[5] It is now distinguished as beingevergreenshrubs withmonocot-typesecondary thickening, shield shaped seeds, and pairedrhipidia with only one to two flowers in each cluster.[5]
SubfamilyIridoideae has the widest geographic distribution and is divided into four tribes and one sister genus:Irideae,Sisyrichieae,Trimezieae,Tigridieae, and Diplarreneae.[5] Iridoideae is differentiated from the other subfamilies by having very short-lived flowers,nectaries on theperianth, and long branchingstyles.[7] Excluding theIrideae, the evolution of oil-producingtrichomes, calledelaiophores, have been gained and lost in each of the tribes attractingoil bees.[10][11][7][12] The genusDiplarreneae is sister to the rest of the subfamily and is unique to Iridoideae in havingzygomorphic flowers andstamens with unequal height.[5]Irideae represents theOld World portion of the subfamily but include several genera that diversified in North America, such asIris.[7] They are distinguishable with the presence of flattenedanthers pressed to thestyle,petaloid crests, andschlerenchyma tissue along themargins of leaves.[7][5]Sisyrichieae is noted for having longstyle branches that may interlace withstamens, partially fusedfilaments, and the lack ofoxaloacetate crystals in leaves.[7][13][5]Trimezieae is the smallest tribe with two to four genera, noted for the presence of largerhizomes orcorms rather thanbulbs as well as a thickenedmidrib.[7][5][14][15][8] Several species with ornamented or iris-like flowers also possess a specialized method of forcing pollen onto heavy pollinators with hinged petals.[16] Tigridieae are distinguished for their large bulbous rootstock andplicate,decidious leaves.[7][5] The number of genera and whether any morphology can distinguish between them has been debated.[17]
Members of Iridaceae occur in a great variety of habitats.Gladiolus gueinzii occurs on the seashore just above the high tide mark within reach of the spray. Most species are adapted to seasonal climates that have a pronounced dry or cold period unfavorable for plant growth and during which the plants are dormant. As a result, most species are deciduous. Evergreen species are restricted to subtropical forests or savanna, temperate grasslands and perennially moistfynbos. A few species grow inmarshes or along streams and some even grow only in the spray of seasonal waterfalls.
The aerial portions of deciduous species die back when the bulb or corm enters dormancy. The plants thus survive periods that are unfavorable for growth by retreating underground. This is particularly useful in grasslands andfynbos, which are adapted to regular burning in the dry season. At this time the plants are dormant and their bulbs or corms are able to survive the heat of the fires underground.Veld fires clear the soil surface of competing vegetation, as well as fertilize it with ash. With the arrival of the first rains, the dormant corms are ready to burst into growth, sending up flowers and stems before they can be shaded out by other vegetation. Many grassland and fynbos irids flower best after fires and somefynbos species will only flower in the season after a fire.
The majority of Iridaceae arepollinated byHymenoptera, frequently by single species or a small group of species.[20] These tight relationships found in individual species of Iridaceae, especially inGladiolus, were the inspiration for the description ofpollinator syndromes.[21] Pollinators include various species ofsolitary bees, as well assunbirds,long-proboscid flies (such asMoegistorhynchus longirostris),[22]butterflies, and nightmoths.[7] Ancestrally, flowers werezygomorphic, as inCrocoideae, with contrastingnectary locations for pollinators.[23] Flowers may presentnectar andpollen rewards to visitors, but some genera may only offer nectar such as inGladious andWatsonia.[4] Species ofFerraria produce putrid smells, floral cups, and dark mottled perianth in order to attract Diptera.[24] Members ofIridoideae andNivenioideae haveradially symmetric trumpet-like flowers that secrete large amounts of nectar. This novel morphology enabled additional floral complexity and rapid evolution of pollinator relationships, as frequently as a new relationship over 5 speciations.[20]New WorldIridoideae represent one of the largestclades offering oil to pollinators, ranging from forced pollination using hinged petals to frequent failure to pollinate.[12] Most of the variability in flowers occurs between subfamilies, includinginflorescence structure, i.e.rhipidia,panicle, orspike, and floral longevity, i.e. less than one day to five days.[20][7] Some members of thetribeIrideae have flowers functioning as meranthia, or developing as three separatezygomorphic units that pollinators visit individually.[4]
69 genera have been recognized in the family, with a total of 2597 species described.[3] TheAfrotropical realm, and in particularSouth Africa, have the greatest diversity of genera.[25]
^"The Iris family: natural history & classification".Choice Reviews Online.46 (12): 46–6794-46-6794. 2009-08-01.doi:10.5860/choice.46-6794 (inactive 1 July 2025).ISSN0009-4978.{{cite journal}}: CS1 maint: DOI inactive as of July 2025 (link)
.jpg)
