Rhododendron Fortunei and Its Allies
By G. G. Nearing
From a talk given before the New York Chapter
When Robert Fortune introduced this rhododendron into cultivation nearly a century ago, having found it in the mountains of eastern China, everyone who saw it in flower must have realized immediately that here was something new and different. It did not create as great a sensation as had R. arboreum from India, because the brilliant red hue of that species has a stronger appeal to the human eye than any other color, while the pale lilac (just off white) of R. fortunei is better attuned to the subtler perceptions of highly educated taste. Nor was fortunei's fragrance a new feature among rhododendrons, for many of the Sikkim species such as maddenii, dalhousiae, auklandii, were even more richly scented. Sir Joseph Hooker had introduced them a few years earlier. These species too have the individual flowers of even larger size than the ample ones of R. fortunei.
What made Fortune's rhododendron unique was the modeling of its corolla, the poise of its flower, a charm difficult to describe, but supremely satisfying even to the eye untrained in appreciation of artistic proportions. The fact that there are seven lobes, instead of the five found in most other flowers of the genus, adds a sumptuousness which contributes still more to its striking beauty.
These seven parts to the flower have been made a leading character by which most of the 34 species are brought together in the Fortunei Series. Sometimes the lobes number only six, sometimes as many as eight, and a few species have five, but the characteristic number for the series is seven. Elsewhere in the genus Rhododendron, very few species have seven corolla lobes, the only ones with this number regularly being auriculatum, galactinum, watsonii, eritimum and metternichii. About 10 other species have seven lobes occasionally.
Strangely enough, it was many years before extensive use of R. fortunei was made by hybridizers. Even in the 1952 Stud Book of The Royal Horticultural Society, out of approximately 1050 hybrids of known parentage, only 173 can be proved to have fortunei anywhere in their breeding. But one or more members of the Fortunei Series entered into the breeding of at least 458. While this list does not include the many hybrids of unknown parentage, the proportion probably holds roughly true for all hybrids except those originating in eastern United States.
During the century that has passed since the introduction of R. fortunei, there have been very few reintroductions, and of the not too numerous plants now going under the name fortunei, there is more than a suspicion that many are actually chance hybrids. The finest selection, 'Mrs. Butler', may be one of these hybrids, though usually assumed to be a superior individual of the species fortunei.
Joseph B. Gable found out many years ago that while a few specimens grown as R. fortunei survived the climate of southern Pennsylvania and flowered well, the great majority proved more or less tender. Some time in the early 1930s, I obtained seeds from his hardiest plant, and raised a crop of seedlings which later were exposed in Ridgewood, N.J. The hundreds which showed winter injury were rejected, and seven or eight of the hardiest grown on. Four of these are now at Mountain Lakes, N. J., where they flower every year and are satisfactorily hardy. All are so similar in their appearance and botanical characters, that I assume them to be true examples of the species, and not hybrid. Seeds from one of these plants have produced a new generation, nearly all of which survive the winters at Ramsey, in extreme northern New Jersey, though it is too soon to say whether all are bud-hardy.
R. fortunei itself will never win much favor with the gardening public, because, just before flowering in early May, it puts out a robust new growth which tends to hide the flowers. The foliage has a fairly good light green color, and the leaves are of good size. The plants tends to make a symmetrical specimen with a stout trunk, and the habit of a small, low tree rather than a shrub. It requires some shade. If grown in a woodland rather than as a specimen, the more open branching gives better visibility for the flowers. In its hardy forms, it is the hardiest fragrant rhododendron species.
Should you question the importance of this fragrance, I can only say that on a still evening at Mountain Lakes when the three plants of fortunei along the house foundations are in full bloom, the porch, the lawn and even the interior of the house if some windows are open, are all pervaded by a scent so delightful that no one with a sense of smell could fail to be enthralled.
Horticultural history was made when Sir Edmund Loder crossed R. fortunei with R. auklandii (griffithianum). It was a lucky cross, much superior to a previous hybrid between the same species, made at Kew Gardens and called 'Kewense'. 'Loderi' has its faults, notably tenderness and a tendency to leggy growth, but the lofty truss of immense florets which inherit the delicate modeling of fortunei, is spectacularly beautiful, deserving the high praise it has won and held undimmed for fifty years.
R. griffithianum was introduced to England from Sikkim about 1850, and usually called auklandii until botanists made a fuss. It can be grown only in the most favorable climates, but because the flower expands to a diameter of sometimes six inches, breeders were not slow to seize upon it, and its influence is plain in most of the large-flowered hybrids now in vogue for mild climates. A member of the Fortunei Series, griffithianum is actually not a close relative of fortunei, having only five corolla lobes.
About the year 1900, E. H. Wilson began sending back from hitherto un-penetrated areas of western China, a series of species much like fortunei and strongly resembling each other. And from time to time other explorers have added still more. A person addicted to common sense would consider most of them variants of a single species, but botanists are different. They count the number of tiny gland-tipped hairs in various parts of the flower, and invent a new species on almost no other grounds. It is as if "scientists" had decided to divide the human race into a number of species according to the amount of hair on the chest and other parts of the body.
Similar to R. fortunei is R. discolor, with leaves a little longer and narrower, and larger flowers appearing in late June. The plant tends to be hardy, but the buds usually winterkill. It has the same fault of putting out new growth before flowering, and is considerably more straggly and leggy. The flower color however varies between pure white and pure pink.
R. decorum, still less hardy, is extremely variable, and so has been separated into several other species. The plant habit of most forms is more compact than in discolor, while the deep green leaves are broader and rounder at both ends. Flowers tend to be much like Fortunei but pure white and appearing in May, often before the new leaves. My own feeling is that a good form of decorum makes a better parent than does Fortunei in the breeding of hybrids, and its inferior hardiness does not necessarily carry over into its offspring. The foliage of Fortunei hybrids is often sparse and yellowish, while decorum hybrids are much more likely to have attractive leaves, and to flower before the new growth puts out. However, there are very poor forms of decorum. A breeder should take pains to select the most attractive specimen obtainable.
Both discolor and decorum have been used extensively in breeding, but it is too soon to evaluate their influence as compared with that of fortunei and griffithianum, which had a start of half a century. However, most of the Dexter hybrids are derived from these four species variously intercrossed. The records are few, almost non-existent, but Mr. Dexter explained to me his general lines of breeding, and I only wish that I had made notes, since memory cannot be relied on after twenty years. He did not stress, as I do, the importance of including in every final cross a considerable element of hardiness. Preliminary crosses must in some cases do without the hardy element, and perhaps, in his own thoughts, Mr. Dexter may have held some tens of thousands of his hybrids to be preliminary. But if hardy hybrids are wanted, then at least one fourth of the parentage should be R. catawbiense or one-half an ironclad hybrid. Or of course, if you consider R. maximum worth using, it can be substituted for catawbiense, though I have yet to see a maximum hybrid worth propagating.
Mr. Dexter used other members of the Fortunei Series. I remember his mentioning R. fargesii, R. oreodoxa and R. vernicosum, but to what extent these species entered into his surviving hybrids, I have no means of knowing.
Joseph B. Gable has also leaned heavily on the Fortunei Series. 'Beaufort', 'Katherine Dalton', 'Gable's Pink No. 1', 'Ladifor' and 'Sir James' are half fortunei, 'Disca' and 'Cadis' at least half discolor, 'Madonna' half decorum. 'Gretchen' contains both decorum and griffithianum. 'Caroline', though of unknown parentage, looks as if it derives its long leaves from discolor.
Had it not been for the flood of 1945, my own list of hybrids would include many bred from fortunei, decorum and griffithianum, and every year now I make extensive use of the pollen of 'Loderi King George: Among my busiest seed parents are catawbiense X decorum, fortunei X croceum, campylocarpum X decorum, discolor X catawbiense.
Going farther afield in the Fortunei Series, small seedlings of R. oreodoxa are showing unexpected hardiness here in Ramsey. If they continue to winter without injury, and if, finally, they bring through a high percentage of flower buds, this attractive species may have to be added to the all too short list of hardies. But my experience with R. fargesii has been less encouraging.>
R. diaprepes has been described as a larger and finer decorum, but even less hardy. It can hardly be expected to contribute much to our hybrids in eastern United States. Tender too is R. houlstonii, scarcely distinguishable from R. fortunei, or, let us say, distinguishable by a hair.
Desirable for its tree-like habit and long leaves would be R. calophytum, but I have never been able to grow it to flowering size, even in the pit. It has few points in common with other members of the Fortunei Series, but was cast out of the Grande Series because of the nakedness of its leaves, and botanists had to place it somewhere. In nearly every other respect it shows alliance with R. grande, but the hairs had to be split, and we find it here among strangers. I cannot say that I consider this species beautiful. Rather it should be called striking. Since the species itself has eluded me, I am pinning my faith on a little plant of 'Avalanche' (calophytum X 'Loderi') coming along in my cold pit.
As Avalanche carries high credentials, I intend to cross it, when it blooms (if it ever does), with discolor X white catawbiense, and twenty years after that, perhaps a very beautiful combination of the parents may flower. I shall not be more than 95 or 100 years old at the time.
Somewhere between R. fortunei and R. calophytum in many respects is R. sutchuenense, but the corolla has only five lobes as opposed to fortunei's seven and calophytum's seven or fewer. The color too, a rather harsh purplish rose, fails to suggest membership in this exclusive clan. Gable considers it hardy at Stewartstown, Pa., but a plant obtained from his has grown only about six inches here in six years. I have no plans for it.
Another outlier placed in the fortunei series without much reason except that its corolla does have seven lobes, is R. orbiculare. This has recently been considered in some detail in the pages of a previous issue, and requires no further discussion here.
Of a dozen or so other species that fall into the Fortunei Series, some are not in cultivation, others I have not seen in flower, and have no clear opinion of their merit.
In spite of all this wealth of material available for hybridizing, we have no fragrant hybrid on the market which can compare in hardiness with the ironclads - that is, survive at 25 or 30 below zero and retain its buds at 20 below, as the hardiest hybrids do. Nor is there any ironclad to compare in size of floret with R. fortunei. It may be that some of the Dexter hybrids will eventually prove hardy enough to qualify on these two points, or perhaps one of Gable's newer varieties may answer.
Fragrance has been so conspicuously lacking in the older hybrids, and is so desirable a quality for any ornamental shrub, that a fully hardy, fragrant rhododendron possessing all the other traits of the best varieties, would be certain of an enthusiastic reception from the gardening public. If in addition it had an immense floret, shapely truss and good color, it would surely captivate most of the millions who garden in our climate.
Hundreds of thousands of seedlings have been raised in the attempt to secure such a hybrid, and sooner or later it is almost certain to appear. But the Fortunei Series hybrids, while offering these eminently desirable features, bring with them also a number of tendencies to be avoided.
One is the almost universal fault of bringing forth foliage shoots before the flowers. No matter how desirable the blossom, it will never win public favor if hidden by leaves. Fortunei and discolor hybrids are especially prone to this failing, while some forms of decorum tend to avoid it, and Griffithianum hybrids often restrain their foliage buds well. As plants grow older and set increasing numbers of flower buds, there is a tendency to hold back the new growth, so that the appearance of a few green tips among the flowers of a small plant need not entirely condemn it. It should also be noted that some of the best ironclads, such as 'Boule de Neige', under certain weather conditions, will start into leaf growth long before the flowers have faded. Breeders should strive to create varieties of equal hardiness and merit, free from this fault, and if the tendency of leaf growth to hide the flowers is strong, no variety will ever live it down.
Equally undesirable is the premature wilting of flowers in hot weather, a habit of discolor and griffithianum seedlings particularly. In our eastern climate, days when the thermometer rises above 80 degrees or even above 90 are not infrequent in May. If the flowers flop down under such conditions, even though they may expand again in the cool of evening, the beauty of the plant in flower is completely cancelled for that day.
Less to be condemned is the naturally floppy, open-topped truss characteristic of much of the Fortunei Series, which contrasts with the dome shaped cluster that lends such striking and majestic grandeur to the best catawbiense and arboreum hybrids. No declaration on the part of modernist aesthetes can successfully deny that the domed truss creates a pattern of outstanding beauty. But neither can we ignore the fact that the free and graceful bearing of the Fortunei flowers has a beauty of its own, in keeping with the larger and more voluptuously modeled flowers, and in fact it would be difficult to display such flowers adequately in the rigid catawbiense truss.
Some plants drop their flowers within two or three days after opening, while others retain theirs for as much as two weeks. Certain decorum hybrids have extremely short-lived flowers, and this trait can bar a variety from popular favor. Flowers should last in good condition for at least a week.
Very large and fleshy flowers such as those of griffithianum and discolor often bruise and turn brown along the edges after being exposed to even a slight breeze. Needless to say, the rhododendron grower does not want to waste his time on such un-ornamental misfits. Flowers need not only to last well, but to continue looking fresh while they do last.
Fortunei hybrids have a strong tendency toward yellowish leaves, while the strongest greens are usually found among the descendants of decorum and discolor. This is strange because the leaf of fortunei itself is decidedly blue-green rather than yellow-green. However, many different crosses of Fortunei show a decided yellow-green turning to almost pure yellow in strong sunlight. A pleasing shade of foliage is of course one of the most important assets of a good hybrid. However, Fortunei Series hybrids in general show good resistance to leaf diseases - a very strong point in their favor, as it is one of the chief weaknesses of caucasicum hybrids.
The leaves of discolor and griffithianum hybrids tend to generous size, especially length, but usually last only one year. The best foliage effects are secured where leaves remain on the plant two or three seasons, and this is a strong argument in favor of the catawbiense hybrids, which often retain their leaves well. A happy combination of catawbiense with one of the Fortunei Series should eventually overcome this very serious drawback. Still another fault of most of the Fortunei Series is ungainly growth habit, unwillingness to make the repeated branching which result in that most desirable of shrub forms, the compact dome. But it should be noted that R. thomsonii, R. arboreum, R. maximum, and even R. catawbiense give hybrids which commonly offend in this respect. R. fortunei itself is a shapelier grower than most of its allies, though forms of decorum often develop well. Worst of them all is discolor.
With so many special beauties and corresponding drawbacks, it is small wonder that the Fortunei Series has been slow so produce for us the outstanding hardy hybrids of which it seems capable. Perhaps another decade or two will be needed, but surely a horticultural masterpiece is somewhere in the making.