QBARS - v8n2 The Naming of Rhododendrons

The Naming of Rhododendrons
By J. Harold Clarke
Chairman, Committee Nomenclature and Awards

The accurate and permanent naming of horticultural varieties is of importance to everyone interested in plants. For many years it has been the custom to use Latin names for botanical groups and non-Latin, common, or fancy names for garden forms. As the botanists have evolved rules for classifying and naming wild plants so have the horticulturists for plants under cultivation.

As a matter of fact, the naming of horticultural plants has been discussed at various International Horticultural Congresses since 1864. A code or set of rules was gradually developed culminating in the International Code of Nomenclature for Cultivated Plants, adopted in London in 1952 by the Thirteenth International Horticultural Congress. Briefly the aim of this Code is "to promote uniformity, accuracy, and fixity in the use of the names with the minimum disturbance of existing nomenclature and methods."

The new Code was published in the Report of the Thirteenth International Horticultural Congress (1952), pp. 3668. Reprints may be secured from the Royal Horticultural Society for one shilling. The Code was put in final form by a distinguished committee of botanists and horticulturists including two Rhododendron specialists, Dr. J. McQueen Cowan of Edinburgh and Dr. Clement Bowers of Maine, N. Y.

The question has been raised as to how this new Code should affect the American Rhododendron Society. Undoubtedly it should be respected and its rules followed but should it be "adopted" by the A.R.S. as its official code? My answer would be "No." It was designed primarily to apply to technical publications and is too long and complicated to interest the average gardener. Significantly Mr. W. T. Stearn, Secretary to the International Committee, says in a foreword to the Code "Specialist societies should use it as a basis for their own codes of nomenclature." The American Rhododendron Society already has a Code. published in preliminary form in the Bulletin for July, 1949, adopted by the Directors August 19, 1949, and reprinted in condensed form in the Bulletin for April, 1951. My feeling is that the A.R.S. Code should be revised somewhat to make it as useful as possible to breeders, nurserymen. and amateur gardeners. It should be kept as simple as possible and should agree in general with the International Code.

The number of American Rhododendron breeders is increasing every year and there will be many new varieties to be named. I am suggesting, later in this article, a revised Code, to be presented eventually to the Board of Directors for adoption, probably with amendments suggested by members who read this article. The nomenclature of the botanical groups, species, etc., will, of course, be left to the botanists with the hope that they will proceed as rapidly as possible to clarify the doubtful species and that thereafter the species names may remain unchanged.

The Term Cultivar

Before outlining the proposed A.R.S. Code it might be well to discuss briefly a few important points in the International Code in so far as they might affect rhododendrons. The International Code recommends that the term "variety" should be confined to those groups below species rank in the wild and commonly known as botanical varieties. For all types of horticultural or garden varieties the term "cultivar" is recommended. Since in American horticultural practice the usual horticultural variety of woody shrubs, such as Rhododendrons and Azaleas, is a clone, the terms cultivar and clone as applied to Rhododendrons may be considered synonymous. In technical writing we may expect to see the term cultivar used almost exclusively, and more and more in popular writing.

The "Group Varieties"

It has been the custom in the past for many English breeders and a few American breeders to give a group designation to all the plants derived from a cross between two species or between a species and a "variety" listed in the stud book. For example the name 'Fabia' includes all the seedlings raised at any time and anywhere from the cross of R. dichroanthum x R. griersonianum . In fact the new Code states that such collective designations shall include all subsequent generations from the first cross, crosses within those generations, and backcrosses with either parent. Where two rhododendron species of rather diverse type are crossed, and second and third generations raised, it would seem that there would be so much diversity in the progeny that the use of a single name to indicate the entire group would be of no value whatsoever.

The new International Code does suggest that these collective designations he used only with some word such as "hybrids" or "crosses" to clearly indicate the collective nature of the phrase. Hence one should write R. (Fabia hybrids, or Fabia crosses) 'Tangerine' or R. (dichroanthum x griersonianum) 'Tangerine,' and not R. 'Fabia' var. 'Tangerine.' Furthermore "When for a cross between two species the describer has decided to publish a collective name, it is particularly important that either before or at the same time he should give a cultivar name to each particular form of the hybrid that he considers worth distinguishing even if there exists only one such form."

These collective designations, because they have been commonly used without an accompanying word or symbol to show their collective nature have been indistinguishable from clone names and hence have led to much confusion and no little dissatisfaction on the part of buyers of Rhododendrons who thought they were buying a clone and found they were buying a seedling. Accordingly the American Rhododendron Society has taken a strong stand against the use of such group names as indicated in its published code. It has also suggested that nurseries listing the "group varieties," of which there are many in the trade, should print the statement appearing at the end of the code. The collective term means practically nothing unless one knows the formula for which it stands, hence would seem to be superfluous in ordinary nomenclatural problems with Rhododendrons. In the case of hybrids originating under cultivation in this country therefore it is strongly recommended that the formula, as R. 'Pink Pearl' x' Betty Wormald', or R. dichroanthum x R. griersonianum , be used rather than a collective designation.

It is felt that the American Rhododendron Society Code can recommend against the using of collective designations, as being unnecessary and likely to cause confusion, without in-any way going counter to the International Code.

The International Code recommends that the two components of a formula he placed in alphabetical order with the female parent, if known, being indicated by the sign Q and the male by d . It has been the custom in this country to place the female parent first and that should still be permissible provided it is indicated in the particular publication that that usage is being followed.

Words formed by combining parts of the Latin names of the parent species, as Grierdal, should not be used as cultivar names. They have frequently been used as collective designations but the International Code requires that Latin descriptions be published to validate such names.

Hybrid groups such as the Ghent azaleas are probably best designated by the English terms for horticultural purposes. The International Code has provision for Latin names for such groups if desired and also for other groups such as graft chimeras which will probably be of little use in the rhododendron field.

The International Code strongly recommends the setting up of an international registration authority, for each important group of cultivated plants, which would maintain a register of all existing valid names. It has been suggested by the Horticultural Council that the American Horticultural Society, which recently published the Azalea Handbook, should set up an international register for Azaleas. At the present time there is no register for rhododendrons in this country other than the one which has been started by the American Rhododendron Society.

The International Code states that, within the same genus, the same cultivar-name is not to be used for more than one cultivar hence the same name should never be used for an azalea if it has been used for a rhododendron and vice versa.

Proposed American Rhododendron Society Code of Nomenclature for Cultivated Plants

Accurate names are important to all concerned with Rhododendrons, the amateur grower, the breeder and the nurseryman. The provisions of this Code, if followed, should help to eliminate confusion and error and certain abuses which have occurred in the past. Such abuses have included renaming or the giving of new names to old varieties, the giving of old names to new varieties, the selling of seedlings as named varieties under the name of the mother parent. etc.

  1. Seedlings not quite good enough to be named, if distributed at all, should be sold simply as seedlings for mass plantings. The inferior plants should be destroyed.
  2. New rhododendron cultivars (horticultural varieties) should be introduced only as clones. The naming of collective groups, to include all the offspring of a particular cross seems superfluous, is contrary to general American horticultural practice, at least, in the field of woody plants, and should not be done.
  3. If it is desired to indicate parentage in published descriptions the formula should be used so it would be R. (dichroanthum x griersonianum) 'Tangerine'. Where a group is already well known, it might be stated that 'Tangerine' is a clone selected from the Fabia group or is one of the Fabia hybrids but it should not be written Fabia var. 'Tangerine.'
  4. A new cultivar should be adequately described, both as to plant and flower characters, in some accepted publication (as the A.R.S. Bulletin) using the R. H. S. color charts in the preparation of the color description. The parentage should be given for the benefit of other breeders. Publication in a catalog is acceptable if there is a description and the catalog is dated.
  5. No name which has been previously used should be used again. No name which has been used for an azalea should be used for a rhododendron and vice versa.
  6. The correct name for a cultivar is the earliest legitimate name; cultivars should not be renamed.
  7. It is suggested that names should be simple and descriptive or meaningful. They should preferably be of one word although two are permissible. Under no circumstances should cultivars be given Latin names. Old cultivar names in Latin may be retained but should be printed in Roman type with 'single quotation marks' whereas the botanical names in Latin are ordinarily printed in italics.
  8. Names which should be avoided include those with single letters, the articles a and the, and titles such as Mr., Mrs., Dr., Capt., etc. Certainly if there is a Mr. Brown Rhododendron then one should not be named Mrs. Brown. Names of States or Countries, without another word should not be used. Names likely to be confused as Caroline and Carolina, and those which exaggerate, as 'Best of All' should be avoided.
  9. A cultivar should not be named after a living person without his consent.
  10. Breeders are asked to present proposed names and descriptions to the American Rhododendron Society to be added to its check list. If the name were one which had been previously used the breeder would be requested to choose another name. The American Rhododendron Society does not name new cultivars for breeders, nor can it prevent breeders from using any names they may wish. It may suggest that certain proposed names do not conform to the Code.
  11. Catalogs and articles listing foreign cultivars should ordinarily use the foreign names "as is" and not in translated form. However where a foreign name would cause some difficulty it may be permissible to change the name, in which case the new name becomes a 'commercial' synonym and when published should be followed by an indication of the original name.
  12. In view of the fact that there are already many "group varieties" in commerce they must be indicated in some way. It is suggested that in retail catalogs which list any of these groups they should be marked "gr." and the following statement should be printed in the catalog:

Rhododendron Nomenclature

Two types of horticultural varieties of rhododendrons are in the nursery trade. The first type includes those cultivars (horticultural varieties) which have been propagated asexually by cuttings, layers, or grafts from one original selected seedling. Such cultivars are called clones and all plants of such a cultivar have identical characters except as they are influenced by environment. The second type of horticultural variety consists of a group of seedlings of a particular cross, usually between two species, or between a species and a "variety." Such "group varieties" exhibit more or less variation, so that two plants of such a "variety" may be quite different

As recommended in the American Rhododendron Society Code of Nomenclature, we are marking all "group varieties" by the abbreviation "gr." All cultivars not so marked are clones. All special award cultivars, marked P. A., T. G. C., A. M,, F.C.C., etc. are clones which have been propagated asexually from the original plant receiving the award.