|Iris are an incredibly diverse group of bulbs and rhizomes, encompassing over 200 species and numerous cultivars. They range widely in cultural requirements, some are drought tolerant, while others require a pond to flourish. Flower color and size vary dramatically as well. Foliage is grass-like or sword-like, and flowers are complex, very showy.
The three inner segments(known as standards) are petals, the outer ones(known as falls) are sepals. There are three main categories of irises: bearded, beardless and crested. Bearded iris are the most popular and well known, and come in virtually every color. The iris borer is a serious pest, found east of the Rockies in Canada, south to Washington, D.C. west to Iowa. Small piles of "sawdust" near the iris rhizome, is the sign of iris borer.
Where winter temperatures remain above 10F, it is absent or rare. It is a larval form of a moth, the main prevention is a good fall garden cleanup of debris where larva can overwinter. I. histrioides is a Reticulata iris similar to I. histrio but more vigorous. Blooms early in the spring with dark blue flowers. This species is very unusual as each fall is spotted deeper blue in the center and has a yellow central ridge with square-sectioned leaves. This is a bulbous iris and does good in well-drained, neutral or slightly alkaline soil in full sun. 'Major' a Reticulata iris bears deep blue flowers.