Carl Phetteplace, M.D.
Fig. 42. A close up of the flower of 'Hawk Crest'. This photo,
taken in 1963, shows quite well the flower shape and type of this
yellow variety pictured on our front cover.
Photo by Carl Phetteplace, M.D.
Like the ancient alchemist ever searching for the secret of making gold it seems that rhododendron growers everywhere have dreamed about creating a hybrid that is a beautiful, true yellow. Although a number of the older hybrids have been classified as yellow, such as the many of R. campylocarpum heritage for example, none could be truthfully considered more yellow than cream or perhaps pale lemon or primrose, although many are very nice.
About or soon after 1950 some of our visitors to English shows and gardens reported the best yellow seen was 'Hawk' and that var. 'Crest' was outstanding. About that time Jock Brydon and John Henny imported 'Hawk Jarvis Bay' and 'Hawk Crest' from the Exbury Estates, but of course there was no material for distribution for some time. About 1957 after the first plant received had been used for cuttings for a few years it was given to me, and I was told that it could be considered the largest 'Crest' (shown on our Front Cover) in North America since it was the first here. Despite the heavy cutting it had been subjected to it was still thin and weak in structure, although the foliage was deep green and attractive. It first flowered in May 1961 at the time the International Rhododendron Conference visitors were here. It was still of very open growth, and I recall Dr. Harold Fletcher commenting as he saw it that it looked "almost too well bred." He later wrote that he doubted if it would live long. I quite agreed with him. Each year, however, it has taken on a more lusty appearance from many new branches breaking out all along the trunk almost to the ground level, with a growth of six to twelve inches on each terminal. It is now over eight feet tall and at least six feet across. There has been no damage to buds or growth at a temperature of plus 10° F. Each year it has flowered with increasing abundance, and this spring had about 50 trusses which are of medium size and compactness, well shaped, with rather open flowers as large as four inches across. It is described as "a fine sulphur yellow" (H.C.C. 1/3). The substance is good, and trusses look well as long as three weeks.
Several Forms of 'Hawk'
The cross was made by Mr. Rothschild of Exbury, using 'Lady Bessborough' and R. wardii, and it received an award of merit from the R. H. S. in 1949. Several sister seedlings have been named including vars. 'Amour', 'Beaulieu', 'Jarvis Bay', 'Kestrel' and 'Merlin'. Of these I have 'Jarvis Bay' only. Although fairly compact as a plant it is a much slower grower in my garden and generally smaller in all its parts. The flowers, of good color, are more funnel-shaped. It is much less attractive generally.
I have not tried to root cuttings of 'Crest' but have made a number of grafts for some of my friends on Fortunei series root stock, both in soft wood through the summer as described by Lem, Larson and others, and also hard wood grafts in early spring. These have all been done in the open field only, covering them for a while with a plastic bag, and in the shade. There are almost no failures and by the second year they are quite vigorous.
When 'Crest' is in full flower it is about the only rhododendron in the garden that gets much attention from visitors, and this may also be said as well of the seasoned rhododendron "experts" as of those quite unfamiliar with the genus. The "well bred" appearance of the plant combined with the clear radiance of the yellow trusses is striking. Perhaps the fact that each truss is almost exactly the same unmixed yellow during the two weeks or more it lasts adds to the beauty. All the trusses therefore present a fairly uniform appearance throughout the blooming season.
Breeding for Yellows
I have used it in hybridizing with several things just for fun, mostly with other yellow hybrids. Among them are 'China', 'Yellow Creek', 'Jalisco', 'Prelude', 'Penjerrick', 'Fawn', 'Naomi', 'Idealist' and an unnamed R. decorum hybrid that has been an unusually good parent. 'Crest' X 'Jalisco' is the only one that has flowered as yet, which was last spring. It looks as if it might become a fairly good rhododendron for both plant and flower, but the color is a clear primrose yellow, much paler than 'Crest'. I doubt if any of these crosses will be as good as the parent.
Some hybridizers have stated that they believed we will only get a real good yellow by starting with R. dichroanthum. I think some very good yellows have been produced by this route and perhaps more and better ones are to come. At the risk of some who are much more knowledgeable sharply disagreeing with me, I am going to suggest that the quality of yellow derived from R. dichroanthum breeding, though yellow, is often more dingy or dull than that obtained from species in the Thomsonii series, especially R. wardii.
Dichroanthum-derived yellows often begin with a strong mixture of pink or red with the yellow. The red fades out first, but also the yellow becomes weaker as the truss gets older. Consequently at no time does the flowered plant present a clear, uniform appearance.
The better forms of R. wardii have not been used nearly so long or extensively as R. dichroanthum and its hybrids (see Rhododendron Handbook 1964, part II). Certainly R. wardii, such as the Ludlow and Sheriff form for example, should produce much more beautiful shrubs and larger, more open flowers and better trusses. Such yellows as are obtained, I believe, are more likely to be clear and radiant.
Species of the Fortunei Series
It would seem that some of the best garden hybrids of the future might well come from the interbreeding of members of the Fortunei series with the Thomsonii species, especially the better forms of R. wardii and/or campylocarpum. R. discolor (the wording meaning "of various colors") is a very fine parent as evidenced by the fact that its progeny have now won five F.C.C. awards by the R. H. S. and twenty A. M. awards. Further the discolor hybrids, especially 'Lady Bessborough', have been good parents. Discolor seems especially good for yellow hybrids, probably because there is really quite a little yellow deep in the corolla as a rule, although it is mainly white with pink shading.
If I were a hybridizer seriously trying to produce another good yellow, I believe I would turn to R. caloxanthum ("of beautiful yellow color") in quest for something to bring more yellow pigment into the blood lines, rather than R. dichroanthum. It is a much better plant, and the good forms perhaps have as much unmixed yellow as any elipidote rhododendron in cultivation and the color holds up well. For some reason I am not aware of its having been used extensively while R. dichroanthum ("two colored flower") and its hybrids have been used very extensively. Perhaps the better forms of R. wardii have not been used widely enough either to fully reveal their possibilities. In time there will undoubtedly be a number of much better yellows than we have previously known.
It may be that 'Crest' will point the way to a more effective direction of breeding.