Stirring the Nomenclatural Pot
Donald H. Voss
Not quite by accident I recently checked the printed registration descriptions of the Robin Hill azaleas and came across variant spellings of the cultivar name 'Vervaeneanum'. After some checking with American Rhododendron Society plant name registrar Jay Murray and learning that the name of the person commemorated is spelled "Vervaene," I stumbled (quite by accident) on the following note published at the end of the plant registry section of the Spring 1980 issue of the ARS Quarterly Bulletin (Vol. 34, No.2): As is Soulangiana (Magnolia) often misspelled Soulangeana, the Indian azalea name is properly spelled 'Vervaeniana', not Vervaeneana or Vervaenana.
Wrong (doubly)! 'Soulangeana' and 'Vervaeneanum' are correct. The International Code of Nomenclature for Cultivated Plants - 1980 states in Article 28: The orthography of words in Latin form which are used as cultivar names should be in accordance with the Botanical Code; if not, the spelling should be corrected. Example (b) of Article 28 states: "Cultivar names, when adjectival in form, should agree in gender with the generic name concerned..." (The -an- form of the endings identify the names considered here as adjectival.)
Regarding epithets formed from modern (in contrast to Greek, Latin, or well established Latin-form) personal names, the International Code of Botanical Nomenclature (Tokyo Code)  in Article 60.11 and Recommendation 60C.1 provides that: If the personal name ends with a vowel, adjectival epithets are formed by adding -an-plus the nominative singular inflection appropriate for the gender of the generic name...except when the personal name ends with -a in which case -n- plus the appropriate inflection is added...
This rule was in force under the Botanical Code adopted at Leningrad in 1975, antedating the note in the ARS Quarterly Bulletin quoted above. Although the examples in the Cultivated Code do not illustrate this aspect of the formation of adjectival epithets, the Botanical Code is explicit on the matter. Thus, for the personal names Soulange and Vervaene, we have Magnolia x Soulangeana (feminine ending in genus Magnolia) and Rhododendron 'Vervaeneanum' (neuter ending in genus Rhododendron). The author has checked this conclusion with Dr. A.C. Leslie, Senior Registrar, the Royal Horticultural Society. He states (personal communication): "We earlier had the spelling of 'Vervaeneanum' incorrect in the Register, but this has now been amended."