JARS v39n2 - The Many Faces Of Rhododendron campylogynum

The Many Faces Of Rhododendron campylogynum
Felice Blake, Kallista, Vic, Australia
Reprinted from the Victoria Chapter Newsletter

The taxonomists would have us believe that the incomparable Rhododendron campylogynum is merely one variable species - but taxonomists rarely seem to be horticulturists! Any discerning gardener can espy and appreciate the myriad subtle differences, as well as the more obvious ones, in the wonderful collection of plants which masquerades under the collective name of Rhododendron campylogynum . Even the name, particularly to the uninitiated, does not give any hint of the delicate charm and fascination of this delightful group of plants. The word 'campylogynum' as many of us know means 'with bent ovary', what a dull and unimaginative and ungraceful name this is, but these delectable little plants must be saddled with it in perpetuity.
Most forms of this so very variable species grow only to about 45 cms., (18 inches), have small dark shiny aromatic leaves, obovate to oblanceolate in shape, glaucous below (except for var. cremastum which has leaves pale green below), and most distinctive looking, even when not in flower. The flowers are nodding, campanulate - like little bells - held up on long pedicels, in small trusses, or sometimes singly or in pairs, with sharply bent styles. The variety in colour is delightful, ranging from plum red, plum purple, red, salmon pink, light rose pink, to creamy white.

It is interesting, however, to seek out the 'history' of this species. It was first discovered in June, 1883, by Abb Jean Delavay in the Tali Range in China's Yunnan province, the home of so many glorious rhododendrons, and was named in 1885 in Paris by Adrien Franchet (Bull. Soc. Bot. France) who was the culprit in saddling this species with the rather ugly name. But the species are first introduced by Forrest in 1912, and was also reintroduced by Kingdon-Ward, Rock, Farrer, Ludlow with Sherriff and Elliot, and Y from various areas in Yunnan, Tibet (now Xizang province of China)and Burma. This species generally grows at altitudes ranging from 2,500 to 4,800 m. so in one of the most alpine of rhododendrons, and grows in some of the wettest parts of the Himalayan region. It has at times been known as R. glauco-album , R. damascenum , R. cerasiflorum , R. rubriflorum and R. caeruleo-glaucum as named by the collectors. And what an impact it must have made on these great explorers, as E.H.M. Cox wrote in Farrer's Last Journey - "Imagine yard upon yard of turf cushioned with masses of small, shining, dark-green leaves, out of which rise delicate glandular flower-stalks. From each hangs a single little bell-shaped trumpet of sculptured wax, a deep mahogany inside and a claret exterior that is covered with the bloom of a purple plum. There is another form, a uniform claret-mahogany inside and out. There in those hills this delicious morsel with its elfin grace flowers year after year at a season when it never sees the sun: and yet it so obviously enjoys life. Such is R. myrtilloides ." How could one better this description?

Apart from the form originally known as R. campylogynum , by 1930 several forms were given specific status viz. R. charopoeum (with larger flowers), myrtilloides (the much dwarfer form of Cox's description) and cremastum (with green under-surface to the leaves). But by 1954 Davidian had reviewed the series and all the previously separate species came under the general umbrella of R. campylogynum as detailed in the Royal Horticultural Society's publication The Rhododendron and Camellia Year Book of that year, with varieties celsum (a taller growing form), charopoeum , cremastum and myrtilloides listed. This was confirmed in the year 1967 edition of the R.H.S. The Rhododendron Handbook Part One Rhododendron Species in general cultivation.

That most expert grower of dwarfs, the late Captain Collingwood Ingram, V.M.H., who grew his collection at Beneden, Kent, England, felt so strongly that some of the forms of this species were so distinct that he published what he considered separate species and this was recorded in the R.H.S. The Rhododendron and Camellia Yearbook in 1969. The well-known form called 'Bodnant Red' was so different to the type species in Ingram's view that he considered it a separate species R. amphichlorum , whilst the little white form he called R. campylogynum var. leucanthum , and the small soft rose pink form he called R. campylogynum var. eupodum . But alas these have not been recognized by the authorities. Ingram's account of the forms of R. campylogynum certainly makes fascinating reading, and one can always feel an affinity with him when he tried so hard to gain recognition of some of the outstanding forms as distinct species and varieties.

Back in 1954 Davidian wrote "In cultivation, however, the extreme forms, though linked by intermediate, are so distinct, that it is advantageous to distinguish a number of varieties." But in his new book The Rhododendron Species Volume 1 - Lepidotes , Davidian recognizes apart from R. campylogynum itself, the varieties celsum , charopoeum and myrtilloides , whilst he now considers R. cremastum as a separate species.

However, now, of course, with Dr. Cullen's new classification as detailed in Notes from the Royal Botanic Garden Edinburgh Volume 39 No. 1 , we are back to just one variable species with no varieties.
In my own garden I grow quite a variety of 'campylogynums', and they are a real joy, particularly in flower, and I grow most of them grouped in one area in the rock garden with shade from the hottest afternoon summer sun, well mulched and well watered in summer, remembering that this species comes from a high rainfall area, but well drained.

There is such a wonderful variety of forms that the enthusiast will seek out all he or she can find. R. campylogynum itself comes in various plummy shades including "the colour and bloom of a muscatel raisin", light rose pink and salmon pink. The clone 'Patricia' sports plum-red flowers and is a good addition to the collection. Then there is the 'Crushed Strawberry' form, but unlike most 'campylogynums', with me this form is unusually slow to flower. Captain Collingwood Ingram's var. leucanthum with its delightful little creamy white bells seems to me closer to var. myrtilloides than to R. campylogynum itself, and is a great favourite in my garden. Then to var. myrtilloides , in Kingdon-Ward's words "a dwarf which deserves attention. It is one of the 'Campylogynum' series, an elegant little plant with boxlike foliage, aromatic, dark green above, and bright silver below. The twin flowers are hoisted well above the foamy leaves on slender pedicels, and in sunshine are the colour of port wine, though with a slight bluish bloom on the outside. Extensive cushions, bristling with these little pouting flowers, may be seen amongst the rocks." Var. myrtilloides comes in other colours too, including a purple form and a most delightful pink form, which is one of my peat garden's treasures. Var. cremastum seems quite, quite different, with leaves light green on both sides. One form which I imported has little purple bells, whilst the other is the well-known 'Bodnant Red' form - in our climate this is not quite so easy to grow as other forms of campylogynum, so I now propagate it every few years to make quite sure I do not lose it.

Var. charopoeum with its bigger flowers has plum-purple or pale rose flowers, and var. celsum is the taller growing one with pink flowers. Of course, this does not cover all the forms that are grown, and the enthusiast will always keep a keen watch to add more to his collection.
Then to come to hybrids, or maybe they are selected clones, or crosses between the many widely varying forms of this so variable species. Flowering before most 'campylogynums' is R. 'Canada'. I imported this from the U.S.A. some years ago, as of "unknown parentage but probably a campylogynum hybrid". Well, it certainly looks like one of the family with bright rose pink bells, rounded leaves with plain green undersurfaces, and red stems. This is a most floriferous rhododendron, and it flowers about two years from a cutting, and in my view one of the most worthwhile dwarfs. Another hybrid R. 'Kim' is reported to be a cross between R. campylogynum and R. campylogynum var. cremastum . This is an interesting one, salmon in bud, but turning a soft yellow, certainly a colour break within this species.
Of course, the hybridizers are now making more use of R. campylogynum as a parent. The white form has been crossed with R. luteiflorum to form R. 'Merganser' which is rather like a large 'campylogynum' with yellow flowers. Then too the 'Bodnant Red' form has been crossed with R. calostrotum Gigha' to make a nearly red bell called R. 'Grouse', and the white form of R. campylogynum has also been used again, this time married to the white form of R. racemosum resulting in white bells on a compact plant called R. 'Egret'. No doubt we will be hearing more from the hybridizers in the future.
R. campylogynum is quite easy to propagate, with cuttings taken from semi-ripe wood in mid to late summer, using about .25% IB Acid, and inserted in peat and coarse sand in a heated propagating box, preferably with misting.
As can be seen, there are many faces to R. campylogynum , and these charmers are most valuable additions to our rock and peat gardens, and add an air of distinction all the year around. They can also be grown in pots for quite a few years, preferably in a very peaty mix. In the garden they team up with the autumn flowering gentians such as Gentiana sino-ornata , and hybrids such as G. 'Kingfisher' making a ground cover, and with their brilliant blue flowers adding interest when the rhododendrons are not in bloom. I also grow galanthus and erythroniums nearby for late winter and spring colour together with other suitable small plants to add interest for the rest of the year.
You will have noted that I have used the familiar 'varieties' to distinguish the various forms of this species. Of course. The Royal Horticultural Society has devised a horticultural revision to cover the old 'varieties', but to some of us this revision seems rather cumbersome, not so much perhaps with regard to R. campylogynum , where we finish up with R. campylogynum Celsum Group, Charopaeum Group (note the amended spelling), Cremastum Group and Myrtilloides Group. But when we consider the fate imposed by the horticultural revision on that fascinating little charmer, R. cephalanthum var. crebreflorum , which finished up as R. cephalanthum ssp. cephalanthum Crebreflorum Group, one must surely wonder if a much more simple method could be found. One could hope that, perhaps, the International Conference will provide the solution!