No iris devotee can hope to realize the full pleasure of his delightful avocation until he has made crosses and produced seedlings of his own. There is something closely akin to parental pride in the thrill experienced when a seedling of one's own production "makes good"; yet strangely enough, for every serious hybridizer there are dozens of eager and equally serious collectors. The reason for this apparent lack of interest in hybridization is, I believe, because few iris collectors realize how ridiculously simple it is to make crosses and produce seedlings.
It is no trick at all to make a cross. Simply expose the stigmatic surface by raising the covering organ or "flap" and dust the exposed surface profusely with mature pollen of the desired male. To do this I simply rub a well opened stamen over the exposed surface. The lacy terminal appendage, sometimes called the crest, affords a convenient "handle" for the lifting operation. Incidentally the term "crest" as used above refers to something entirely different from what we ordinarily mean by "crest" in Louisiana irises.
To guard against accidental contamination, stamens of the female blossom should be carefully removed from six to 24 hours before the blossom would normally open. At that stage the stigma is highly receptive, therefore, emasculation and pollination can be done at the same time. To insure against later contamination by way of insects and other natural agents, it is customary to bag the fertilized flower. F or this purpose, I have found a muslin bag about five inches wide and ten inches long very satisfactory. After the bag has been placed over the flower, the open end is wrapped around the stem to prevent the entrance of insects and held in place by means of a short piece of thin copper wire coiled several times around it.
A high percentage of seed pods produced under natural conditions never reach maturity. Immature pods occasionally suffer from insect damage but the most important predators are field rats and other rodents who seem to have a particular fondness for maturing seed pods, especially the ones you are trying to save for seed. As the seeds develop the stem is gradually pulled down by the weight of terminal pods which usually touch the ground in the advanced stages. This is not only an invitation for rats to help themselves, but sometimes causes rotting of the pods under damp conditions.
Staking has not proved entirely satisfactory. Rats climb the stakes and help themselves without invitation. Besides, I have found that the weight of the pods frequently causes breakage of the stem at the point of support.
I have had very good success by loosely wrapping each pod at an intermediate stage of development in a small piece of ordinary wire screen, and allowing the plant to droop naturally under the weight of the pods. In addition to preventing damage from rats the screen will help to keep the pods out of direct contact with the soil thus tending to reduce rotting. As a further precaution the pod may be held in a position a little above the ground by a support applied directly to the encasing screen.
I have not tried poisoning as a means of preventing damage to seed pods, but feel that the method is well worth considering. Stomach poisons could be used with relative safety as I don't know of anything worth having around the place that will eat iris pods. Iris seed permitted to ripen to a dry condition on the plant will go into what is known as a "resting stage". When planted in such a condition the seeds require from one to three years to germinate.
The problem of speeding up germination has been solved in a very simple manner. We found that seed removed from the pod at an appropriate stage prior to complete maturity and planted immediately will ordinarily give from 60 to 90% germination during the following fall and winter. The seed should be taken out when approximately 113 to 112 of the pod-surface is still green. At that stage the seed coat will be cream to pink in color.
For germinating the seed I recommend using cans opened at both ends sunk almost completely in the ground and filled with a half-and-half mixture of sand and well pulverized garden soil. ANo. 2 can will satisfactorily accommodate up to 100 seeds, which should be covered with approximately one inch of the soil mixture. Germination will be somewhat earlier if the seed bed is shaded. The soil should be kept moist but not soggy.
Seedlings should be moved to nurseries when three to four inches high. Nursery spacing 15 inches in both directions is considered about right but I have used much closer placement at times when necessary to conserve space.
Removal of selected seedlings from the nursery to garden beds should be done at the earliest possible moment to prevent mixtures. After selections have been completed it is then necessary to remove the discards from the nursery area to make room for the new seedlings coming along. This is the hardest job of the whole business. It is of course difficult at times to draw the line between a selection and a discard, and as mentioned above, one who produces seedlings with his own hands develops a sort of parental solicitude for them and just hates to see any of them go. But this is a most . necessary (if sometimes heart-breaking) procedure, as the accumulation of seedlings would soon crowd everything else off of the place. I sometimes find "foster homes" among kind friends for some of these "dis-placed" seedlings that are simply "too good to throwaway."
The problem of inheritance of color, color pattern and other characteristics in Louisiana iris is now essentially a wide open field and this fascinating study has no doubt many thrills in store for the professional geneticist as well as for the amateur breeder. In this connection the following observations which I have made in connection with my own breeding work are mentioned for whatever the information may be worth to the reader.
Seedlings from the cross MARINGOUIN FULVA X KRAEMER YELLOW were all yellow. Many of these are considered superior to either of the parents. The one seedling I obtained by selfing Maringouin yellow is yellow.
Yellow crossed with some other color usually disappears completely in the first generation and reappears in the second generation in a ratio much wider than the simple Mendelian 3: I (Probably in a ratio of 63 non-yellow to one yellow or wider). As an exception to the above rule, certain of my F 1 seedlings (notably EDITH DUPRE) from the cross MARINGOUIN FULVA X BAZETI are intermediate in color.
The order of blooming succession among various forms of Louisiana iris is commonly downward. The terminal bud opens first and the ones below bloom later in successive order. But in certain forms of 1. brevicaulis the order is reversed, that is, the lowest bud blooms first. In a cross between a form of 1. brevicaulis of the latter sort and MARINGOUIN FULVA which blooms from the top downward, I obtained some seedlings (e.g. Louise Austin) which, while following the usual downward order, bloom in much quicker succession than normal. It is as if the opposing tendencies compromised by having all the blossoms open nearly at the same time.
As to possibilities for further improvement, I feel very definitely that we have, up to now, merely scratched the surface. The infinite variety of colors, blooming qualities, growth habits, not to mention various degrees of vigor, disease resistance, "gardenability," and numerous other characteristic found in diverse natural forms are the building blocks out of which our "super aristocrats" are to be created by painstaking but highly satisfying work of future hybridizers. Yes, iris breeding can be a lot of fun. Why don't you try it?
George Arceneaux was a charter member of the Society for Louisiana Irises (SLI). He was the collector of an important I.fulva which he used extensively in breeding new cultivars. This article originally appeared in the April 1947 issue of Home Gardening and was printed in the Spring 2007 issue of the Fleur de Lis, the quarterly publication of SLI.