Rhododendron Breeding
F. W. Schumacher, Sandwich, Mass.
Words and deeds of long ago have a fascinating influence on people centuries later. Some writings of the controversial Roman poet, Ovid, had such an effect on me.
"In nova fert animus mutatas dicere formas
." This line from the poet's work, "Metamorphoses," refers to the tendency of the human mind to express itself always in new creations different from the old. It was a wise teacher, indeed, who explained the meaning of these words and pointed out their implications to his class.
As far as deeds are concerned, the accomplishments of plant breeders of the past deserve minute examination by the would-be breeders of the present. When we take a close look at breeding work done with rhododendrons today, we must admit that we are not really doing breeding work but, more correctly, hybridizing mainly.
We are making first-generation crosses by the hundreds and are satisfied. Many of our English friends have set the example and we follow in their steps. Their Studbook listings of recent introductions practically all refer to first-generation hybrids. Theirs is an impressive list and the possibility of being included in it and named as originator of a new cross must be a temptation to all who do hybridizing work.
But, we ask, is hybridizing enough to create really beautiful rhododendrons after the manner of the best English introductions, rhododendrons hardy enough to withstand the rigors of winters in the Eastern part of this country? Anyone acquainted with the results of recent breeding must answer that it probably is not. It seems that we must go to work and employ breeding principles which are not at all complicated but, in fact, quite simple.
The best hardy rhododendrons for Eastern conditions, the old
R. catawbiense
hybrids and some of the newer Dutch and English hybrids on the borderline of hardiness, cannot be defined exactly as to what went into their make-up. Are these hybrids the result of breeding work done along definite lines? If so, the secret of the sequence of their development passed away with their originators. Many of these varieties are still popular nearly a hundred years after their introduction. We wonder how many of the present named Studbook hybrids will be grown a hundred years from now.
In our scramble to get our names into the Studbook we seem to have lost our sense of direction in spite of known objectives. What are these directions as far as plant breeding is concerned? How many generations stand behind even the oldest of our present-day rhododendron varieties? A very few only. How many generations stand behind the development of Camellias or Tree Peonies, for instance? The answer is "Many."
Almost all of us over the age of three score and some will remember what tomatoes were like in our childhood days. There is a vast difference between modern tomatoes and those we knew fifty years ago. How many generations stand between the old and the new fruit? It took between 40 and 50 generations to perfect the modern tomato and approximately twice that number occurred since the plant was introduced into cultivation.
Should not a rhododendron breeder's achievement be measured, not so much by the new varieties he contributed to the Studbook list, but rather by the number of generations he added to the breeding of the plant? Instead of featuring the new varieties of a breeder, we should try to find out how he went about producing them. We should stress the necessity of continuing his work, adding generations to the material he developed.
It is only natural for a man who has devoted much of his time to rhododendron breeding to expect results and their recognition during his lifetime, along with financial returns from his labors. But can real accomplishment be reached within the short span of a man's life, considering the conditions into which his breeding work has to be fitted?
What is the proper approach if he wants to achieve his goal?
The answer lies in the study of breeding work done by our predecessors. Fairly recent examples of breeding work can be found among the French breeders of garden roses, work which started about 150 years ago and still continues.
The modern rose breeder finds it comparatively easy to develop a succession of new and interesting varieties, yet many of the choicest new roses make poor garden plants. Breeding procedures strayed from the path of hardiness to ever more tender varieties among the hybrid tea roses.
How is it that today's rosarians find it so easy to produce new material? The answer is that our modern roses all are the result of breeding work done many years ago. A number of French breeders contributed. How did these men proceed?
One of the earliest lessons these men learned was that little progress could be made with cross-breeding alone. Rose species do not cross with one another as readily as rhododendron species do. Year after year a cross may fail until finally a 'break" occurs. Possibly a single hip is set, sometimes holding only a single seed. A start was made from such "breaks." These breeders first task was to find plants to use as female parents which would set seed prolifically. Often they used for this purpose plants which had no value in themselves as garden plants but which could be expected to take pollen readily from other varieties and to set seed in quantity or which showed promise with other good features.
It is such parent material that led to the fecundity of our modern roses, making it easy for the breeders of today to raise seedlings in quantity for selection.
New roses appeared in fair numbers in France only when early breeders started to gather open-pollinated seeds from separate varieties and grew batches of seedlings. These breeders well understood that from a cross made between two high-quality parent plants, the desired results almost invariably were not obtainable in the first (Fl) generation. First-generation material was usually found to be inferior to the parents.
It was their most closely-kept secret that the desired results were quite readily obtained when these first-generation plants were cross-pollinated among each other. The improvements then would occur in the seedlings of succeeding generations.
It is at these stages that the breeder should rely entirely upon the natural forces of heredity without attempting further in-crossing with other material. It is line breeding which has produced the modern Delphiniums and hardy garden Primroses in America. It is line breeding which will produce the rhododendrons of tomorrow.
Very little of such work has so far been done with rhododendrons. We may surmise that early English and, more lately, the Dutch breeders and the Belgian originators of Indica Azaleas proceeded along these lines. Much noteworthy breeding work was done before our day. However, the chain of development usually was broken when a breeder died, leaving no one willing or able to carry on.
Many of these broken chains are at our disposal today with the great number of named varieties of known parentage. It behooves us to feel a sense of responsibility, not so much to insist on our own ways of producing something new and worthwhile all of our own creation, but to include in our work the "loose ends" left to us as the heritage from departed plantsmen.
The French breeders of roses were first and foremost plantsmen. They did not concentrate solely on actual breeding work. They raised seedlings from parent species and hybrids for observation and for later selection of promising plants to be included in their breeding work.
Never before has there been such opportunity for doing rewarding work as with the rhododendron material now at hand. Aspiring plantsmen no doubt are well on the way today toward creation of the better rhododendrons of tomorrow.
As this article was being readied for the Bulletin, David G. Leach's wonderful book, "Rhododendrons of the World," came to hand. Mr. Leach in a long chapter concerned with breeding has set forth very ably and in great detail the points which these notes touch upon.