Flower Forms of Japanese Iris

By Chad Harris

The iris family Japanese iris, Iris ensata has the most diverse flower forms of any other iris. This diversity has been achieved under the watchful eye of hybridizers in Japan over several hundred years of selective breeding, working with mutations within a single species.

Areas in Japan that bred Japanese iris with different flower forms

Secrecy of breeding stock within the different groups in Japan and the regional taste of perfecting what the perfect flower form should be, gave rise to distinct forms. Container growing for indoor display or garden growing for outdoor viewing also led to distinct flower forms of Iris ensata.

Typical three fall form of a wild type Japanese iris

The typical flower forms found in the wilds are smaller blooms of three falls, three standards, and three style arms. It is easy to remember flower parts of the iris as falls are the petals that hang or fall down, while the standards are the petals that stand upright. The style arms are the central part of the iris flower housing all of the reproductive organs female and male.

Nagai style of flower blooming in a Japanese iris garden

Nagai possibly the oldest flower form found in Japan. This area is known for its wild iris that had more variation in flower colors and patterns.

Nagai form is simple, showing variation in colors and patterns

The flower forms found here are simpler, being collected wild iris that had caught the eye of a collector.

Elevated walkway to be able to look down upon the iris flowers

Edo ancient name of Tokyo is where growers developed different flower forms some with multiple falls. Plants from this area of Japan were meant to be grown in the garden and seen from a higher elevation looking down upon the flower.

Three fall Edo flower form

Six fall or double flower form of the Edo style

Nine fall flower with the horizontal flower form of the Edo style

To get the maximum viewing pleasure of viewing from above, many flower forms whether single (3 falls), double (6 falls), or multi-falls (9+ falls) generally are held in the more horizontal linear line of a plate.

Ise flower form the three falls are pendent

Ise style and form meant to be grown in containers and brought indoors for display. This distinctive form embraces only the three fall variety of bloom. The falls to be seen from the side were bred to be pendent and hang straight down from the haft or shoulder of the bloom. These plants are shorter with the bloom stem at or slightly below the foliage height thus cradling or to seemingly hold the flower.

Higo indoor display

From the southern island the Kumamoto or Higo form was bred. Due to the heavy rains at bloom time these plants were also grown in containers like the Ise flowers to be displayed indoors during bloom.

Higo three fall flower form

Six fall Higo flower form with large style arms and flaring crests

The 3 fall, 6 fall, or multi-fall blooms being viewed from the side were also bred with arching falls, however, not as severe as the Ise form. These are large flowers with very large style arms and upright crests being the “heart” of the flower.

Ball form of the Japanese iris

There are also recognized flower forms that we today would call novelty. The “Ball” form is a flower that does not open fully staying in the balloon stage, or slightly opening up as Yae-gyokuhoren.

The raptors talons of the claw form

The “Claw” form is very self-describing. Do you see the raptors claws?

Hose-n-Hose is one flower inside of another

Rare is the true Hose-n-Hose form. This flower may look at first glance to be a multi-fall bloom, however, look at the placement of the pollen anthers and you will discover that this is truly one flower inside or on top of another. These flowers do not have any seed in the ovaries, they only show layers of more flower parts (petals) one on top of another.

Multiple style arms and crests a form being embraced in the United States

Fast becoming a modern favorite flower form here in the United States is the “Multi-Style Arm”. When the anthers become extra style arms, they make for a tight tuft in the center of the flower. This does have drawbacks as there usually is no pollen to be found. It is also difficult to find which correct style arm to put pollen on for future breeding of the flower. I do not know if this form is found or embraced in Japan and would like to hear from other growers.

For further reading on this subject: The Japanese Iris, by Currier McEwen; Classic Irises and the men and women who created them (chapter 4), by Clarence E. Mahan; and The Japan Iris Society web-site at http://www.japan-iris.org, here you will find English written papers by Hiroshi Shimizu.