Three Members of the R. Fortunei Series At Crystal Lake Springs Island
by Rudolph Henny
These notes with reference to the three species R. sutchuenense, R. calophytum and R. discolor are no attempt to prove superiority over the other plants of the series R. Fortunei, so well represented in the Trial Garden, but is rather a limited discourse of the interesting aspects of each individual. Other plants of the R. Fortunei series as R. fortunei itself, R. griffithianum, R. orbiculare, R. diaprepes, the variable R. decorum and R. fargesii are fine species and would not be overlooked in evaluating the series. More than likely though R. fortunei and R. griffithianum are the most spectacular of the entire series.
If the month of February has been kind, with only a hint of mildness, R. sutchuenense will respond with a swelling of buds, and within the first weeks of March some bloom will be apparent. Occasionally I have seen bloom on R. sutchuenense in the last week of February, and during a mild winter the last flowers on R. mucronulatum have hardly fallen before R. sutchuenense presents itself. It has been assumed, though possibly erroneous, that the bloom of R. sutchuenense can actually withstand several degrees of frost. Of course, such may actually not be the case, but in years past I have seen the bloom of R. sutchuenense caught in a light frost, where the foliage has been lightly iced, and the bloom escape undamaged in the subsequent thaw. During the winter of 1951 the large plant of R. sutchuenense was in full bloom when a light snowfall of three inches covered the plant late in the evening. A light frost followed during the night, but the next day the bloom were uncovered by noon and appeared undamaged. One realizes of course, that snow is an insulator against frost, but snow itself as an insulator is very near freezing and the covering too light for total protection. After a wait of several days there was very little browning of flowers and since other new bloom had opened the effect of frost was negligible. I have never placed a thermometer in a plant for a reading, but year after year a light frost, will hardly damage the flowers on this species whereas the corolla on R. dauricum, R. mucronulatum and R. moupinense are destroyed during the night. Actually that the bloom can withstand freezing and subsequent thawing is to be doubted, but the illusion persists and nature does her best to protect this early species. There are a number of factors involved in this curious protection of bloom and they are directly responsible for the protection afforded. R. sutchuenense never blooms early in its life, and a plant is usually anywhere from six to eight feet in height, and ten to twelve years of age before it bears its first bloom. This fact alone would afford no little protection from low lying light frosts that wreck havoc with the smaller plants. Frost pockets are not always present in identical parts of the garden, and their idiosyncrasies change with each different condition of atmosphere. Generally speaking though it is safe to assume that the lowest parts of the garden are most vulnerable to attack. Since a large percentage of the first bloom is formed within the confines of the foliage, and literally speaking within the plant rather than on the outside perimeter, is another advantage endowed by nature to protect the first bloom. The last buds to open are usually on the outside of the plant where no protection is afforded by foliage and limbs. This combination of height and protection furnished by the plant itself are the factors that do most to protect the bloom in the light frosts that ordinarily destroy the blossom of other plants.
No new growth appears on R. sutchuenense for several weeks after all bloom has disappeared. In many plants of the R. fortunei series that bloom later when frost is less apt to appear the new growth often hides the bloom, for the new growth and buds appear at the same time. This feature detracts from any plant, but it certainly shows nature's attempt at protection where it is needed. Nature is content to send out flowers in late winter, so placed that they may be able to withstand light frost if only by subterfuge, but withholds the very vulnerable new growth for weeks later in R. sutchuenense. Is the gardener amiss to state that R. sutchuenense bloom will withstand light frost?
Gardeners also are aware of another perplexing though minor problem e.g. the confusion that exists between R. praevernum a species closely allied to R. sutchuenense, and R. sutchuenense var. geraldii. That the two species and the variety are misnamed in numerous cases is clearly apparent. The corolla of R. praevernum is of a pink color with a dark wine red basal blotch. R. sutchuenense has rose pink bloom without a blotch according to "The Species Of Rhododendron", but in mentioning R. sutchuenense var. geraldii confusion begins for it also has a basal blotch as does R. praevernum. In recent years the entire group has seemingly been placed into the one species group viz. R. sutchuenense or its variety by nurserymen and gardeners alike. Shipments of plants from abroad have also shown a mixture of the species, and whatever has been at hand has apparently been shipped to gardeners here.
Many of the large specimens of R. sutchuenense and its variety along with R. praevernum were obtained from the Barto gardens, but in all cases the plants were of remarkable uniformity and all were rightly named the var. geraldii. Since the mark of identification is the hairy midrib, the two species should ordinarily be easily identified if it were not for the var. geraldii. In Dr. Cowan's "The Rhododendron Leaf" a description and illustration of the magnified hair found on the midrib of the leaf R. Sutchuenense is shown on plate VIII b. It is hoped that this winter the small group of members who have had the training will be able to identify the species with the aid of Dr. Cowan's edition.
The foliage of the entire so called R. sutchuenense group has a most remarkable resistance to winds, which ordinarily damage the foliage of comparable plants. Strong winds during that short period in the spring when growth is tender and unfolding can reduce the new foliage to a pitiful shambles for the entire year. It is advisable to place protection about the plant if such conditions are only apt to arise, and that is yearly if the location is in the open, but aside from that short period the plants and foliage will withstand more abuse from winds than many.
R. calophytum, a most notable plant for the larger garden or woodland, blooms during the first week in April, and escapes many of the vicissitudes and vagaries of the early spring that befall R. sutchuenense. The handsome and exotic appearing foliage of R. calophytum seem to bespeak tenderness, but such is far from the case. The species is quite hardy and suffered not at all from the severe frost of 1950. Since the leaves of R. calophytum are often over a foot long on a well grown specimen, an open windy location should not even be considered, for only reasonable. strong winds will literally defoliate the plant. Unlike R. sutchuenense, R. calophytum must have complete protection from winds and even some protection from the hot sun. Several years ago while moving a three foot high plant of R. calophytum on an open truck and without protection from the wind, I saw every leaf removed on arrival and this after a trip of less than thirty miles. The driver assured me that his speed was less than 35 miles an hour. The weakest part of the leaf seems to be the petiole or stem. In a strong wind the leaves revolve in a more or less circular motion and eventually twist off and disappear. I might add that several plants of R. augustinii on the same truck were not damaged. The corolla of R. calophytum is not as large as the bloom of the finer forms of R. Sutchuenense. With me it has always been a vagrant anticipatory assumption as to why nature did not bestow R. calophytum, such an outstanding foliage plant with flowers nearer the size of a magnolia bloom. This idea seems to adhere even after I have seen R. calophytum bloom many times.
The last number of this trio of the R. fortunei group is R. discolor. Apart from the fine bloom and habit of this species I would like to assign these few notes to the hardiness of this plant. In The Rhododendron Handbook 1947", which applies to the British Isles, R. discolor is appraised as "not satisfactory in cold places in the British Isles where it is apt to split its bark." I can state that here on the Pacific coast I have never seen a plant of R. discolor with its bark split due to freezing, nor have I ever heard of a single instance of it. Plants of R. discolor are now near twenty years old here and the -15 F. of 1950 neither killed the plants or damaged the bark. I cannot help but be impressed with the following of following implicitly hardiness ratings that are applicable to widely separated sections of the country. It is true that the gardener in a limited way does obtain a general idea of hardiness from any such report, but in many instances he will be dismayed at its inaccuracy. Ten or twelve years ago R. discolor was watched over quite alternatively for evidence of bark splitting, and it was generally agreed that the first real freeze would remove the plant from the scene.
The A.R.S. is aware of its own hardiness report as published in The Bulletin Vol. 5, No. 1 as being applicable on the Pacific Coast, but no more applicable in the Eastern United States than the British ratings are on the Pacific Coast. It is to be hoped that the Eastern members of the A.R.S. will undertake a hardiness report for the benefit of members and a general overall summation would be of much more value than one covering an isolated district. The more rigorous winters of the East would establish: plant hardiness that could never be attained here or in Britain.
From my observation I am aware of only a few other species that can withstand as much exposure to the sun and outright neglect as R. discolor. This reference is to established plants of some size and does not refer to a small plant just recently set in the garden. During the war years hundreds of plants of R. discolor were growing atop a hill at the Barto nursery without care or water. Many of these plants were four feet in height and were well budded, and not at all unhappy.
Last winter Dr. Clark showed color slides of the old Dexter nursery on the East coast at a meeting of the A.R.S., and many plants that remain are hybrids that Dexter made by using members of the R. fortunei group as parents. I was greatly impressed that the plants still survive after some years of neglect. I am not aware that Mr. Dexter used R. discolor in his hybridization, but I have read that he used R. fortunei very freely.
I would like to mention one other member of the R. fortunei series viz. R. decorum a dark pink form that was a high favorite with me, but was cut to the ground during the 1950 freeze. To mention that R. discolor is now my favorite of the entire series would not be far amiss, for in truth I cannot compare it to R. fortunei which plant I have never seen. I dislike mentioning repeatedly that here again is a case of every garden having a different R. fortunei. The large, recently, planted plants of R. fortunei at Crystal Lake Springs Island are quite variable. It must be assumed that many of the plants in the series are referred to as belonging to the R. fortunei group and during the passage of years all are eventually R. fortunei. "The Species Of Rhododendron" bespeaks of R. fortunei as being rare in cultivation although introduced as long ago as 1855. Many types of the series are now being assembled in the Trial Garden and it is hoped that a report of their true identity will be forthcoming in the near future.
Before closing these notes on R. discolor, some mention should be made of varietal differences within the species. For many years reports have persisted that the pink form of R. discolor was the most desirable, and that such a plant does exist, I do not doubt, but after watching hundreds of plants come into flower at the Barto Nursery for just such color I can state that I never saw one. Five years ago I made a hurried check of about seventy plants in bloom, and their uniformity amazed me. Each was white with a yellowish tube, with some slight spotting on the upper lobe. The seventy plants could have been passed as asexually propagated clones rather than seedlings. The flowers on the entire group came out a very pale pink and quickly changed to white. Mrs. Barto informed me that to her knowledge none of the many hundreds had ever bloomed pink. A description of R. discolor in "The Species Of Rhododendron" makes no mention of a pink form in its description of the species; but "The Rhododendron Handbook 1947" states the following "Flowers either white or pink."