Aril Iris.

Aril Iris.

It was 2014 and my passion for gardening was well on the way to becoming an obsession, when I first saw a picture of Iris acutiloba ssp. lineolata. It was love at first sight but that excitement soon turned to disappointment when I tried to track one down. It was immediately apparent that this plant is very rare in cultivation, particularly in Australia.

My searching eventually led me to discover the Scottish Rock Garden Club forum and my eyes were opened to the entire section of Oncocyclus within the genus Iris. Each more exquisite than the last, all of the Oncocyclus are beautiful plants. They are native to a range centred around the Caucasus mountains, Georgia, Armenia and Azerbaijan in the North, Northern Iran and Eastern Turkey, Syria, Jordan, Lebanon, and Israel in the South of the range. Further East are the closely related and equally stunning Regelia section in Turkestan and Afghanistan. The term Aril Iris refers to the section Oncocyclus and section Regelia, both of which have a characteristic fleshy aril on the seed. There are Oncocyclus endemic to habitats ranging from seaside dunes in Israel, seasonally wet grassy hillsides and high, dry, rocky mountains of the Caucasus.

In Australia there is a small community of people growing Oncocyclus and I was thrilled to discover that Pat T. lives in my own state of South Australia, in the Barossa Valley just an hour's drive from me. It was at Pat’s home that I first saw Oncocyclus flowering. Pat encouraged me to join the Aril Society International, which I did and in 2015 I received my first Oncocyclus seed through the annual seed exchange the society organises.

Now what to do with them? I quickly learnt that they have complicated and difficult dormancy. Natural germination rates are very low and slow! Most serious enthusiasts use complicated seed treatment methods like "forced germination”, a process involving carefully cutting the embryo end of the seed, removing the seed coat including the aleurone layer and a small slither of the endosperm exposing the embryo.

Another more technical but more successful method employed to get around the low germination rates is embryo rescue or embryo culture (EC). Typically, this requires access to a laboratory (although it can be done at home with careful preparation and care) and some skills in aseptic technique. As luck would have it, I have worked for 25 years in plant biology labs as a technician and have all the necessary skills. I researched some protocols and set to work with my newly acquired seeds. The process involves surface sterilising the seed and then under sterile conditions dissecting out the embryo (hopefully without damaging it) then placing on agar media to grow. Removing the embryo from the seed like this and providing it with sugar and macro and micro-nutrients means growth starts immediately and they progress rapidly.

Figure 1. Development of the embryo in vitro (annotation in days).

Plants are ready to come out of in vitro culture and be potted up when they outgrow their tubes and have two or three leaves, usually at around 3 months. This is a risky time in the life of a young Iris who has up until now lead a very sheltered and pampered life in a test tube! The process of hardening off needs to be done slowly and without potentially deadly shocks of high temperature or low humidity.

Figure 2. Iris kirkwoodiae, ready for potting up.

Figure 3: Newly potted seedlings, just out of embryo culture being gradually hardened off indoors.

Around the same time as I was doing my first experiments with embryo culture, I started chatting with Otto Fauser on the SRGC forum. One day a parcel arrived from Otto with some plants in it for me and one of those was this incredible little gem, Iris paradoxa, from the Caucasus mountains, North East Turkey, Armenia and Iran. It took my breath away when it flowered in spring 2015, the first ever Oncocyclus iris I had flowered.

Figure 4: Iris paradoxa.

The first of my embryo cultured Irises came into flower in spring 2016, this one is an interspecific hybrid by Jim Kurtz, an American grower; Iris dardanus* x I. iberica ssp. elegantissima (Dardanus = I. korolkowii var. concolor x I. iberica).

Figure 5. A hybrid of Iris iberica ssp. elegantissima and the Regelia iris, korolkowii

Below are a series of hybrid Oncocyclus bred by Pat T. and Dr. Peter Gras, a mentor of mine by correspondence who shared with me not only seeds, but protocols for embryo culture and much knowledge and wisdom of the specifics of growing these plants successfully. These hybrids often have complex parentage, the primary hybrid crossed back to one of the original parents, to a third parent or even to a second primary hybrid. They are generally not named and carry the breeders number designations as shorthand names.

Figures 6 - 9. Interspecific Oncocyclus hybrids in bloom. (Above and below).

Iris mariae x haynei hyb. dark form 

I have to say that these stunning flowers are even better in person than in photographs. Seeing my own plants bloom was highly motivating to cast the net wider for seed, especially the elusive species which have always appealed more to me. It seems that most of the seed on the seed exchange lists were primary hybrids, like those shown above and plenty of ‘aril-breds’ (Oncocyclus species crossed with bearded Irises making them easier garden plants but diluting that aril iris allure).

Species as found in nature have a story to tell of how they have been shaped by the challenges of the environment they find themselves in over millions of years. Their shapes and forms and colours; their strategies to lure insect pollinators and how they ensure that their seed find themselves in a position where they have everything they need to grow and become the next generation of

successful plants. Each individual is a custodian of the genes which are, in a way the soul of the species’ a lineage passed unbroken from parent to sibling over eons of time.

Figure 10. Iris atropurpurea

Iris atropurpurea has the deepest wine coloured flowers with a delicious velvety sheen to them. In their native habitat in Israel they grow on sandy basaltic soils, a stone's throw from the beach. Unfortunately many populations are threatened with extinction by the pressure of development.

More recently I have been fortunate to have been offered seed of some of the rarest and most beautiful species thanks to fellow enthusiasts in the Northern Hemisphere. I am excited to say that I have been lucky with them so far. I have successfully produced some healthy plants, now entering into their second season of growth and doing well. With any luck I may see flowers from a few of these in 2021.

Figure 11. A record of development of one-year old seedlings being potted on.

Figure 12. Iris acutiloba ssp. lineolata

Iris acutiloba ssp. lineolata, the strange and wonderful little iris that started this whole journey for me and now a dream come true. These plants will dazzle you and then break your heart with their tendency to suddenly rot, turning to mush literally overnight. Or worse, they grow well and then succumb to virus. Some will just fail to thrive while their neighbours grow and flower their heads off. Species which you think from your research should be a good fit for your climate may just refuse to grow and others which everyone assures you are devilishly difficult just pop out flowers in a few years, seemingly effortlessly.

You may ask, is it worth all the fuss and the trouble? As lovely as their flowers are, are these fickle mistresses worth the inevitable heartache? I enjoy the challenge and the journey and have never been easily dissuaded by failure. Sure, it would be easier to plant a hanging basket with petunias and admire them from the comfort of a deck chair, with a hot cup of cocoa and a biscuit. But I drink my coffee black and generally prefer kneeling on rocks and weeding my crevice garden to a comfortable chair, so I say yes!

Thank you Jamus S. for this wonderful article, you can follow Jamus_ s on instagram.