Iridaceae (/ɪrɪˈdeɪsiˌaɪ, -siːˌiː/) is a family of plants in order Asparagales, taking its name from the irises. It has a nearly global distribution, with 69 accepted genera with a total of about 2500 species. It includes a number of economically important cultivated plants, such as species of Freesia, Gladiolus, and Crocus, as well as the crop saffron.

Members of this family are perennial plants, with a bulb, corm or rhizome. 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 the blue flag and yellow flag.

The family name comes from the genus Iris, 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 from Olympus to earth along a rainbow, whose colors were seen by Linnaeus in the multi-hued petals of many of the species.

Iridaceae is currently recognized as nested in the Asparagales order but was traditionally grouped with Liliales. Iridaceae was previously divided into four subfamilies but results from phylogenetic analysis suggested an additional three could be recognized. These differences in circumscription are a result of homoplastic traits, including asymmetric corms, woody corm covering, exclusion of the vascular trace during ovule development, and leaf margin. Molecular clock analyses have supported initial cladogenesis in Antarctica-Australasia 82 million years ago (mya) from a Doryanthaceae ancestor. The distribution of subfamilies in Iridaceae is considered to be phylogenetically structured, with all neotropical species belonging to one subfamily, the Irdoideae.

Subfamily Crocoideae is one of the major subfamilies in the family Iridaceae. It contains many genera, including Afrocrocus, Babiana, Chasmanthe, Crocosmia, Crocus, Cyanixia, Devia, Dierama, Duthiastrum, Freesia, Geissorhiza, Gladiolus, Hesperantha, Ixia, Lapeirousia, Melasphaerula, Micranthus, Pillansia, Romulea, Sparaxis, Savannosiphon, Syringodea, Thereianthus, Tritonia, Tritoniopsis, Xenoscapa and Watsonia. They are mainly from Africa, but includes members from Europe and Asia. The rootstock is usually a corm, they have blooms which sometimes have scent, are collected in inflorescence and contain six tepals. The nectar is produced mostly in the base of the bloom from the glands of the ovary, which is where the flower forms a tube-like end. In some species there is no such end and the plant only provides pollen to pollinating insects. Members of this subfamily have the sword-shaped leaves typical of Iridaceae.

Subfamily Isophysidoideae is monotypic, only containing Isophysis from Tasmania. It is the only member of the family with a superior ovary, and it grows a solitary star-like, yellow to brownish flower. It is also sister to all other extant taxa of Iridaceae, diverging 66mya.

Subfamily Nivenioideae contained six genera from South Africa, Australia and Madagascar, including the core genera and only true shrubs in the family (Klattia, Nivenia and Witsenia). Upon phylogenetic analysis, subfamily Crocoideae is always found nested within Nivenioideae, leading to it not being a monophyletic taxon. A revised description of these groups led to the description of Aristea, Geosiris, and Patersonia each as separate subfamilies, retaining a core, monophyletic Nivenioideae. It is now distinguished as being evergreen shrubs with monocot-type secondary thickening, shield shaped seeds, and paired rhipidia with only one to two flowers in each cluster.

Subfamily Iridoideae has the widest geographic distribution and is divided into four tribes and one sister genus: Irideae, Sisyrichieae, Trimezieae, Tigridieae, and Diplarreneae. Iridoideae is differentiated from the other subfamilies by having very short-lived flowers, nectaries on the perianth, and long branching styles. Excluding the Irideae, the evolution of oil-producing trichomes, called elaiophores, have been gained and lost in each of the tribes attracting oil bees. The genus Diplarreneae is sister to the rest of the subfamily and is unique to Iridoideae in having zygomorphic flowers and stamens with unequal height. Irideae represents the Old World portion of the subfamily but include several genera that diversified in North America, such as Iris. They are distinguishable with the presence of flattened anthers pressed to the style, petaloid crests, and schlerenchyma tissue along the margins of leaves. Sisyrichieae is noted for having long style branches that may interlace with stamens, partially fused filaments, and the lack of oxaloacetate crystals in leaves. Trimezieae is the smallest tribe with two to four genera, noted for the presence of large rhizomes or corms rather than bulbs as well as a thickened midrib. Several species with ornamented or iris-like flowers also possess a specialized method of forcing pollen onto heavy pollinators with hinged petals. Tigridieae are distinguished for their large bulbous rootstock and plicate, decidious leaves. The number of genera and whether any morphology can distinguish between them has been debated.