In the terminology of the iris world, this genus is divided into two categories, the bearded ones also called pogon and the beardless types called apogon.

Beardless iris do not have filaments or crests on the fall. They are generally not considered as showy as the bearded iris but they are more adaptable to a wider variety of conditions. Many of them thrive on poorly drained, wet soils and some may be planting in ponds.

There are several subcategories of beardless iris including:

As the name implies, these iris are native to the Gulf Coast area of the Southern United States which makes them hardy in Zones 8 to 10. They grow to about 2 or 3 feet in height and bear flowers that are 3 to 4 inches in size. Bloom colors span a very wide range including white through cream and yellow to bronze, pink, red, blue, purple and near black. Some say Louisiana Iris species have flowers of more different colors in the wild than any other plant. The blooms appear in mid to late spring.

Some of these plants were known for rapidly developing long rhizomes and spreading around the garden. Newer cultivars have been selected to limit this behavior. Louisiana iris do not rebloom.

Another division of this group has been defined as those developed along the Gulf Coast and those found in the Mississippi Delta.

The Iris species included in this group are:

I. hexagona I. fulva

I. follosa I. gigansicaerulea

Flower types in this group of iris range from typical singles with 3 large falls (sepals) to peony like double flowers with 9 or 12 petals. The blooms are described as single, double, triple, multipetaled, monstrosa and novelty. They tend to have flat tops and many are shades or mottled versions of lavender-rose, purple, white and blue.. Most of these cultivars have come from hybridizers in China and Japan who made crosses that include the species I. kaempferi.

These are plants that need an acid soil with a pH in the range of 5.5 to 6.5. Japanese iris like a constant supply of water similar to the requirement by Louisiana iris. In proper growing conditions, they will form a large clump in about 3 or 4 years and may need to be divide to maintain blooming. Unlike some other types of iris, Japanese iris do not rebloom.

Asato Birako' 'Bellender Blue' 'Haku-Botan' 'Nara' 'Oriental Fantasy'

'Pink Pearl' 'Shei Shonagon' 'Waka Murasaki' 'Wine Ruffles'

As the name implies, these plants from the northern climates are very cold hardy and thrive in cooler regions. They grow up to about 3 or 4 feet in height with flowers about 3 inches wide. Most of their blossoms come in deep blue, purple and violet but some of the newer cultivars also bloom yellow. Siberian iris bloom later than the tall bearded iris.

Siberian iris will tolerate wet conditions and may actually be grown in a backyard pond. The thin, grass like foliage is attractive when the plant is not in bloom. Of all the Iris species, this one is probably the most reliable in the home garden.

'Caesar's Brother 'Coronation Anthem' 'Esther C.D.M.' 'High Standards' 'Indy'	'Jeweled Crown' 'Mesa Pearl' 'Orville Fay' 'Roaring Jelly' 'Strawberry Flair'
Repeat Bloomers - These are iris that have a primary bloom time and then will sometimes have some blooms later in the season. "Rebloomers" refers to those that continue to form blossoms throughout the season once they start. The following is a list of Siberian iris that often repeat bloom.
'Lavender Light' 'My Love' 'Reprise'	'Soft Blue' 'Springs Brook'

These are beardless iris that are some of the tallest of all iris growing to a height of 5 feet. There are about 20 species of this type of iris found in the temperate zones of the world such as sunny sites in Siberia.

Spuria iris form large, 4 inch wide flowers in spring and early summer. They come in colors of  white, cream, yellow, brown, blue and purple. Some blooms have a blend of colors with distinctive veins.

Perhaps the key requirement of these plants is a dry summer. In most areas, the summer rains are too much for them to handle. So, they need warm, dry conditions although some species are known to survive in Montana and Minnesota.

Spuria Iris species:
Iris orientalis (Iris ochroleuca) Iris crocea Iris sintenisii Iris graminea
Spuria Iris species - Iris:
'Amber Gleem' 'Color Focus' 'Lady Butterfly' 'Lavender Waves' 'Royal Cadet'	'Snow Giant' 'Sunset Colors' 'Yellowcopter' 'Zulu Chief'

This iris group is appropriately named since most of the species in it will not grow well except in their native environs. In those areas, they grow about 12 to 24 inches in height and have delicate flowers.

I. douglasiana I. innominaia

A species is often defined as a plant that currently resides in the wild or there is evidence such as an herbarium sample that shows that it did in the past. These are not cultivated varieties, i.e. cultivars.

I. confusa (Evansia) I. missouriensis I. tectorum