There are many types of beardless iris and most have rhizomes however several have bulbs instead.
Learn more about Bulbous iris
The "Louisianas" originated in the USA and is a grouping of five species, Iris brevicaulis, Iris fulva, Iris giganticaerulea, Iris hexagona and Iris nelsonii three of which originated in Louisiana with I. brevicaulis and I. fulva native to the Mississippi region. These iris are a clump forming evergreen, water-loving perennial. Their flowers tend to have very wide open petals with brightly coloured style arms. They like wet, acid, humus rich soil, and are often called bog iris. They flower October to December. Their colour range is blue, purple, yellows, white, pink, reddish. They are excellent cut flowers as they have a good bloom life.
This iris is one of the iris in the Louisiana grouping with a distinctive copper-red to deep red flower and bright green leaves. It is perennial with rhizomes. It is endemic to the swamps and wetlands of southern and central United States. It requires wet conditions and prefers acidic, heavy clay soils. It is ideal for shallow water ponds. It likes full sun or part shade.
JAPANESE IRIS Iris ensata
Japanese hybridizers have worked with these iris for over 500 years, creating irises that have most spectacular flowers. Their blooms are usually huge, ruffled and flat in form; some are marbled with gray or white. They bloom about a month after the TBs. Japanese iris require require moist conditions and are ideal for damp shaded areas. They require slightly acid soil. They can be grown in shallow water in pots but need to be taken out of the water when they die back over winter.
Spurias are tall growers with a flower similar to Dutch Iris. They flower from late October through November. They like almost any soils, even alkaline ones. If unwatered through summer they will die down and happily come away in winter, or if lightly watered throughout summer they will stay green. Even though they are hardy plants, do not allow them dry completely out in spring. They are excellent for naturalising and are virtually carefree. They can be left undivided for many years and don't like being moved and may not flower the first year after being moved. Plant 2-5 cm deep in the soil in a spot which get full sun. Like most iris they benefit from an annual fertilising with organic fertiliser.
Siberians perform best with cooler conditions, regular moisture and a slightly acid soil. The blooms can be blue, purple, red-violet or yellow with newer cultivars in brown and orange shades. They have a variety of forms from upright to flat and round. They are most attractive in established clumps that develop a bouquet effect They grow to a height of 2 to 4 feet., although there are some dwarf varieties. Their grass-like foliage after bloom is one of their attractive garden features. They tend to bloom slightly later than the TBs.
PACIFIC COAST IRIS (PCI)
Pacific Coast Natives, or Series Californicae (CA)
These shorter growing iris make a wonderful border plant. PCIs are often the first to flower in spring starting in September and early October. They must have acid soil, liking similar fertiliser and conditions to camellias. They prefer a sunny spot with some afternoon shade in summer. They required moderate watering through summer. They are more fussy about being divided that most other iris and can only be divided in late autumn (May-June). When planting disturb the roots as little as possible and plant so the roots are about 1-2 cm deep.
EVANSIA - CRESTED IRIS
This group includes I tectorum (pictured), I wattii, I japonica, I cristata (below) and I confusa. These irises come from Asia (with the exception of I cristata), mainly south-west China. I tectorum and I cristata which from shorter growing clumps, the others produce tallish plants, often with aerial roots and fans forming 10-20 cm above the ground on bamboo-like stems. They dislike saline conditions and strongly alkaline soils. They do best in conditions similar to camellias, i.e. damp, acid soils, with morning sun and afternoon shade. They are best divided in early winter and can be planted from the rhizomes which break off easily from the base of the fans which have produced aerial roots. In early spring they produce large sprays of dainty frilly blooms. Iris cristata is dormant in winter.
DWARF CRESTED IRIS
OTHER BEARDLESS IRISES
A useful landscaping plant for dry areas in shade or part-sun. Interesting orange berries after flowering and evergreen leaves.
Iris unguicularis (Algerian Iris)
This is an easy to grow iris which mainly have lilac or blue flowers however there are pink and white varieties. Their attraction is that they flower in March through to July.
YELLOW FLAG IRIS
Iris pseudacorus is a vibrant and vigorous plant which has the potential to become weedy. It is a wetland iris and has become invasive in parts of the U.S. Gardeners should cultivate the yellow flag iris in a way that prevents it from escaping into nearby lakes and waterways e.g. in containers rather than in the ground.
Iris laevigata "Colchesterensis"
This is a superb water loving form of the Iris laevigata species. When it reproduces from seed, the offspring comes pleasingly close to the parent. It has gorgeous, sumptuous white flowers, heavily painted in deepest navy blue. It is fine in ordinary garden but outstanding in damp or wet soil or ponds.
Dietes grandiflora is from the Iridaceae Family also known as the large wild iris, African iris or fairy iris. It is a rhizomatous perennial plant with long, rigid, sword-like green leaves. It is used widely in landscaping.