Irises comprise about 200 species of perennial herbs in the family Iridaceae, which also includes crocuses, freesias, and gladioli. Irises are mostly distributed in the northern temperate zone, the majority being native to Asia.Irises are divided into two divisions, those arising from bulbs and those from horizontal underground rhizomes. They have grasslike or swordlike leaves, and large, showy flowers. There are three sepals, known as fails because they usually bearded or crested. Three petals, called standards, alternate with the sepals and are upright. Three styles, which are petallike extensions of the ovary, arch over the base and midsection of each fall. Between each style and fall is a single stamen (male organ). The arrangement of the style and fall ensures cross oillination of the flowers by insects. As an insect moves through the passageway between the style and fall, it deposits pollen from the previous flower on the stigma near the tip of the style. It then reaches the stamen, brushing against the flowers pollen and carrying it off to other flower.
Varieties and Uses
Many horticulturally important species, hybrids, and cultivars are grown. The common garden irises of the United States are usually divided into bearded, beardless, and creted irises, all of which are rhizomatous, and bulbous varieties. Bearded irises are by far the most popular. The Fleur-de-Lis, or German iris, Iris germanica, is the most commonly grown bearded iris. It is a source of orris root, used in perfumes and tooth powders. Although not as popular, many of the beardless irises are also cultivated. Bulbous irises are the florists irises that are grown in greenhouses for cur flowers in winter. Very few crested irises are cultivated in the United States.