Using Species in MDB Breeding, Part 3: Iris reichenbachii x Iris pumila

by Tom Waters

This is the conclusion of a three-part posting describing projects with miniature dwarf bearded (MDB) and standard dwarf bearded (SDB) irises. The first and second installments were posted in July and October 2023. 

My goal for this hybridizing project is to produce a true-breeding line of MDBs that belong to the same fertile family as the SDBs and MDBs from SDB breeding. In theory, using species and species hybrids that are compatible with SDBs will circumvent the tall bearded ancestry that can lead to larger, out-of-class plants. The earlier installments cover the use of Iris lutescens and of a hybrid of Iris aphylla x I. pumila. 

The current post describes work with seedlings from I. reichenbachii x I. pumila. This third avenue of work is, to me, the most exciting and promising. However, I got started with it a bit later than the first two approaches, so it is less far along.

I. reichenbachii is a species native to the Balkan peninsula. It comes in both diploid and tetraploid forms. (The tetraploid species I. balkana is considered a synonym of I. reichenbachii.) Plants typically have very slender stems topped with two buds, ranging in height from about 6 inches to about 12 inches. Flowers are either yellow in color or some blend of violet, brown, and gray. This species is probably best known as a parent of Paul Cook’s famous ‘Progenitor’ (R. 1951), which introduced the dominant bicolor pattern into tall bearded irises.

The tetraploid forms of the species belong to the same fertile family as TBs and I. aphylla. Hence crossing it with I. pumila ought to produce plants compatible with SDBs, just like the aphylla x pumila cross described in part 2.

tetraploid I. reichenbachii ex Mt. Vikos, Greece

I have raised a number of these (cross S026) from crossing a yellow tetraploid I. reichenbachii from Mt. Vikos, Greece, with I. pumila ‘Royal Wonder’ (Coleman, 2013). About half the seedlings are yellow and half are purple. They are all about 5 inches tall, with one or two dainty flowers per stalk. Because I. reichenbachii is so much smaller and daintier than I. aphylla, I believe these plants have even greater potential to produce consistently small and dainty MDBs. I have made as many crosses with them as possible. So far, they are not cooperating as pod parents, although they produce plenty of fertile pollen.

S026-02
I. reichenbachii X 'Royal Wonder'

 

S026-05
I. reichenbachii X 'Royal Wonder'

    

I am eagerly awaiting bloom in 2024 of seedlings from ‘Miniseries’ (Keppel, 2011) X S026-02. Still in the pipeline are crosses of the S026 seedlings with ‘Arson’ (Keppel, 2016, SDB), ‘Come and Get It’ (Black, 2013, SDB), ‘Dollop of Cream’ (Black, 2006), ‘Oh Grow Up’ (Miller, 2018), ‘Pearly Whites’ (Black, 2014), ‘Self Evident’ (Hager, 1997), ‘Tasty Treat’ (Johnson, 2020, SDB), and ‘Pirate’s Apprentice’ (Hager, 2003). 

Multi-generational breeding projects like this one require patience and a certain amount of faith in the theory behind them. It can be a long slog with little immediate gratification. But it can also be very satisfying to pursue curiosity about paths not taken before and to learn as one goes. For me, this type of undertaking matches well with my limited space and my penchant for careful planning. Perhaps in a few more years, the groundwork described in these three posts will yield something worthy of being grown in gardens or meriting the attention of other hybridizers. Until then, the learning itself is a fine reward.

In Pursuit of Variegated Roof Iris

  by Bob Pries

Iris tectorum alba, Pries photo

Iris tectorum (the Japanese roof Iris) is one of the easiest species to grow. Many years ago, I heard about a variegated form and got very excited. In my eyes, the white flowers of Iris tectorum are one of the most enchanting of Iris flowers. Unfortunately, this variegated form was said to have blue flowers. I imagined how stunning the white flowers could be with beautiful variegated foliage.

When I finally saw some plants of this variegated form, I was somewhat disappointed in the quality of the variegation. It was much like some of the variegated, tall-bearded irises that have irregular streaks and stripes. It was, though, much more pronounced than what you see in virus-infected plants. However, the plants themselves were not robust growers, and this clone seems to have died out in cultivation.

There was one troubling fact. The insert image of the blue flowers was not Iris tectorum. At the time, I lived in zone 6 in Missouri. The image I thought looked very much like images I had seen of Iris japonica. But japonica does not tolerate zone 5 winters well. The foliage when received appeared more glossy.

Iris japonica flowers, Hensler photo

 

About the same time that I was eagerly searching for someone who could share a piece, I saw an advertisement in a general garden catalog. It showed an image of beautifully variegated foliage and a small insert of blue flowers. It proclaimed, "Variegated Iris tectorum for sale," so of course I ordered it. But the leaves were more slender than I. tectorum and it appeared I had gained a new house plant.

Variegated Iris japonica Pries photo

In trying to find out more about variegated Iris japonica, I found references that suggested there is more than one form of variegation and at least two types grow in Japan.

The next year I visited a very large perennial nursery outside of St. Louis. The proprietor—who I knew well—was proud to show me a huge planting of variegated Iris tectorum being used as a groundcover. It was absolutely gorgeous. I felt a bit guilty when I told him it was not Iris tectorum but japonica. I warned him it would not make it through the winter but he did not dig it up and it all perished. More and more I kept seeing Iris japonica incorrectly labeled as Iris tectorum in the trade.

Iris japonica, one of three focal points. The others are Brugmansia 'Snowdrift' upper right and variegated Curcuma; Pries photo

Since moving to North Carolina (zone 7) I have grown many forms of Iris japonica. Tony Avent’s Plant Delights Nursery (zone 8) has selected several with differing flower colors. All the green leaf forms survive my winters. They are especially good as groundcovers under the dry shade of Pine trees. But I still love the variegated form which I maintain as a pot plant. It seems just a bit more tender than its green cousin. It is especially attractive as a focal point in my houseplant garden and is a feature of my deck garden of potted plants. I would be delighted to find other forms of the japonica but someday I hope to grow a true variegated tectorum.

Variegated Iris japonica repeats the angular texture of Yucca 'Colorguard' Pries photo

Siberians and Species Irises: Looking Forward to June

By Renee Fraser

It was a great disappointment to those of us who love irises when the Triennial Siberian and Species Iris Convention had to be postponed for a year.  A mild winter and a record hot early spring forced all of the blooms 4-6 weeks early, so the Convention will be held in June of 2013.  As consolation, I asked  Brock Heilman, a talented photographer and member of the Michigan Iris Society, to share a few photos of the gardens to be featured on next year's trek. 

These are some of the gardens that will be available for tours at this year's convention.

Judy Hollingworth, whose husband Bob is a contributor to this blog and a famous hybridizer of Siberian irises, has created this Eden.

Hollingworth Garden

Hybridizers send their creations to gardens where the Conventions will take place, and growers and hybridizers take care of them, sometimes for several years, to assure a spectacular bloom and a wonderful show of new varieties for the convention attendees.

Guest Irises at the Kaufmann Garden

This is not your father's siberian iris!  Look at the incredible colors being created by iris hybridizers.

'Salamander Crossing' (SIB Schafer/Sacks 1999) 

Novel colors and forms of irises are on display at convention gardens.

'Lakeside Ghost' (SPEC I. laevigata Harris 2012)

Astonishing new color combinations are being developed.

'Tipped In Blue' (SIB Schafer/Sacks 2010)

Hollingworth Garden

This is just a taste of the beauty awaiting you.  We hope to see you at the Convention in June 2013.