|New Pink Irises for your Garden|
Courtesy Cooleys 1951 Catalog
One morning in 1942 while inspecting our iris seedlings I was startled when I saw that one of the buds just opening was a deep pink, almost rose red. I had never seen a pure pink iris before, but it had been my dream for many years. Within a few days seven more pink flowers made their appearance among our seedlings, and these eight plants turned out to be the beginning of a new line of pink iris. Twenty-five years ago I realized a pure pink iris would add much to the beauty of flower gardens and made up my mind then to grow one. As most FLOWER GROWER readers know, the breeding of plants is not unlike the breeding of birds, animals or other living things - the same general laws of heredity apply.
Better animals, birds, vegetables and flowers are developed by carefully planned mating. Broadly speaking, "like gets like," but there is always variation in the offspring. To illustrate, let's consider breeding iris. If the objective is color, as it was in my case, a careful study should be made of all the varieties available to determine which two would most likely produce the desired color when crossed.
The selection of this breeding stock is very important and is not based solely on the color of the flowers, but also on the characteristics of their ancestors for several generations. This is not as difficult as it counts for the checklist book of the American Iris Society lists over 19,000 named varieties of iris and, in most cases, their parentage. These carefully planned crosses, to be made the following summer when the iris are in bloom, are frequently worked out by the fireside during the long winter.
In making a cross we take the pollen from the stamen of one selected parent and put it on the stigma of the other. The pollen fertilizes the eggs in the ovary and eventually a seed pod develops to the size and shape of a butternut. This may carry anywhere from a half dozen to 80 seeds. The seed is planted in late fall on open ground in the garden and germinates the following spring. When the young seedlings are about 3 inches high they are usually transplanted to another bed in rows about 18 inches apart and 10 inches apart in the row. Under favourable conditions most of them will bloom the following spring.
All plants from a single seed pod are simply the children of the two selected parents; there will be a general family resemblance but no two plants will produce flowers exactly alike in color, form and texture. As in human families, there is always considerable variation.
|Dave Hall Surveys His Pinks from a Vantage Point on His Terrace|
From these plants, called seedlings, two or more parent plants that come nearest to the color or objective are again selected and crossbred. This process is repeated until the plants become weak from inbreeding. It is then important that there be one or more additional inbred strains or families of similar color, but not closely related, for an outcross with the first so that the resulting seedlings will regain their lost vigor and acquire what is called hybrid vigor. By this process, called line breeding, and careful selection, plus time, patience and faith, wonders can be accomplished in changing and improving any of the characteristics of iris or other plants.
The importance of not mating plants with common faults cannot be overemphasized. In such a case the offspring are almost sure to inherit the faults of both parents. If success did come in producing a new and sensational color in a flower, color alone would be of little value if the bloom lacked good form or substance, or the stem were weak and poorly branched, or the plants were shy-blooming or lacked vigor. So in working for color we must strive for many other desirable and important characteristics. To produce a plant with some of these desirable points is not difficult, but to combine most of them in a single plant is a real achievement.
In time most careful breeders build up several strains or families of their own. By doing this they are able to breed out many of the weak or undesirable points, and at the same time strengthen the desirable characteristics until they become somewhat dominant. This gives the breeder good stock and an intimate knowledge of its good and bad points, representing quite an advantage over a beginner's efforts.
When I started working for a pink iris I gave careful consideration to all of the best near-pink iris of that period finally selecting several varieties of orchid and lavender tones as parents. The offspring of these plants were discouraging. The orchid and lavender tones were dominant, the flowers smaller than I wanted and the substance thin.