International Code of Botanical Nomenclature

(Tokyo Code), Electronic version


This new edition of the International code of botanical nomenclature, like its immediate predecessor, is in English only (British rather than American English, in cases of discrepancy). French, German, and Japanese editions of the text of the Berlin Code were produced separately and it is anticipated that at least French and German editions of the Tokyo Code will be prepared.

The Tokyo Code, is, however, significantly different from the Berlin Code. There are two reasons for this difference: one relates to the arrangement of the book and other technical matters, the other to its content.

Considering arrangement first, the Tokyo Congress agreed to delete the major part of Chapter V dealing with "Retention, choice, and rejection of names and epithets", transferring such material as was not already covered elsewhere in the Code to other Articles, notably Art. 11. With five other Articles deleted from the latter part of the Code at previous Congresses (two in Leningrad in 1975, one in Sydney in 1981, and two in Berlin in 1987), only 11 Articles remained in the Code following Art. 50, yet the numbering extended to 76. For this reason and because a completely new subject index was being prepared for this edition, the Editorial Committee decided that a renumbering of the Articles in the latter part of the Tokyo Code was essential for clarity. This renumbering was executed in the spirit of the Nomenclature Section's usual instruction "to preserve the numbering of Articles and Recommendations in so far as possible", in that only the Articles following Art. 50 have been renumbered, and, by a rearrangement of the ordering of the Articles, the commonly cited Art. 59, on names of fungi with a pleomorphic life cycle, has retained its traditional number. The final Article is now Art. 62, an extra Article having been created by the division of the old Art. 69 (see below).

The Editorial Committee also took the opportunity to clarify the rules on typification and effective publication by creating a more logical arrangement of Art. 7, 8, 9, 10 and 29, 30, 31, respectively. Art. 7 now deals with general matters of typification, Art. 8 with typification of names of species and infraspecific taxa, Art. 9 with the various categories of types applicable to such names, and Art. 10 with the typification of supraspecific names. Art. 29 now addresses the general issue of effective publication, Art. 30 special cases, and Art. 31 the date of effective publication.

Among the more familiar Articles whose numbering has changed are the former Art. 63 on superfluous names, which is now Art. 52. , and the former Art. 69. on nomina rejicienda, which now forms Art. 56 and 57 (see below). A tabular key is provided, setting out the changes in numbering of Articles and Recommendations, as well as their individual paragraphs and Notes, between the Tokyo Code and the Berlin Code. The numbering of the Articles remained virtually unchanged between the Seattle Code adopted in 1969 and the Berlin Code. The Seattle Code includes a "Key to the numbering of the Articles and Recommendations" for the five editions of the Code from Stockholm (1952) to Seattle (1972), and the Stockholm Code includes a similar key comparing its arrangement with that of the Cambridge Rules (1935).

In this edition, the body of the Code is printed in three different type sizes, the Recommendations and Notes being set in somewhat smaller type than are the rules, whereas the type of the Examples is even smaller. This reflects the distinction between the rules (primarily the Articles), the complementary and advisory material (the Notes and Recommendations), and the mainly explanatory material (the Examples). The nature of Articles, Recommendations and Examples is generally well understood, particularly now that voted Examples are designated as such (see below), but the role of Notes is less clear. Like an Article, a Note in the Code states something that is mandatory; it differs from an Article, however, in that a Note does not introduce any new rule or concept, but merely spells out something that may not be evident to the user but is provided for elsewhere in the Code, either explicitly or by implication.

Content, however, is much more important than arrangement or format, although the latter are sometimes the more noticeable. The Tokyo Congress was noteworthy in that conservation of species names and rejection of any name that would cause a disadvantageous nomenclatural change were both accepted by an overwhelming majority on a show of hands. Those who remember the narrow majorities by which conservation of names of species of major economic importance and names which represent the type of a conserved generic name were approved at Sydney and Berlin, respectively, will recognize the fundamental change that took place in botanical nomenclature at Yokohama. The Code is no longer a handicap but an encouragement to the maintenance of nomenclatural stability (see also Greuter & Nicolson in Taxon 42: 925-927. 1993).

The restrictions on conservation of specific names have, therefore, been removed from Art. 14.2, and conservation of the names of species, as for families and genera, now simply "aims at retention of those names which best serve stability of nomenclature". With the adoption by the Tokyo Congress of an amendment to the former Art. 69 that provides for the rejection of any name "that would cause a disadvantageous nomenclatural change", the Article came to cover two distinctly different situations and has been divided into two. The first, the new Art. 56, deals with the general case (i.e. any disadvantageous nomenclatural change) and includes the mechanisms by which names can be rejected as in the previous Art. 69.2. The second, the new Art. 57, relates to the more restricted case, to which the former Art. 69 was hitherto confined, i.e. names that have been widely and persistently used for a taxon or taxa not including their type. Such names continue not to be available for use in a sense that conflicts with current usage, unless and until a proposal to deal with them under the conservation provisions of Art. 14 or the rejection provisions of the new Art. 56 has been submitted and rejected. The separation of Art. 56 and 57 makes even clearer the requirement of the Code (formerly in Art. 69.4) not to use such a name in a sense that conflicts with current usage unless the appropriate Committee has authorized its use.

It is of particular note that the Nomenclature Section at Yokohama, recognizing the significance of this increased scope for conservation and rejection of names in ensuring nomenclatural stability, adopted a resolution in the following terms: "The Section urges the General Committee and through it all Permanent Committees to make full use of the options that the Code now provides in order to ensure nomenclatural clarity and stability." Individual users of the Code also have a responsibility to help ensure nomenclatural clarity and stability by making appropriate proposals for conservation or rejection rather than change names for purely nomenclatural reasons (see also the Congress Resolution, below).

One entirely new concept is incorporated in this edition of the Code, that of interpretative types to serve when an established type cannot be reliably identified for purposes of precise application of a name. The original proposal had used the term "protype" for such a specimen or illustration, but the Nomenclature Section asked the Editorial Committee to determine the most appropriate term and the Committee adopted "epitype" as better expressing the meaning ("on top of the type") and because protype had been used in other senses in the past. The provision appears in Art. 9.7.

Other additions of note decided by the Tokyo Congress and now incorporated in the Code include provision for the use of the term "phylum" as an alternative to divisio (Art. 4.2); the requirement that, on or after 1 January 2000 (subject to the approval of the XVI International Botanical Congress) names be registered (Art. 32.1); the designation of "suppressed works" in which names of certain categories are ruled to be not validly published (Art. 32.8 and the new App. V); and the requirement that in order to be validly published a name of a new taxon of fossil plants must, on or after 1 January 1996, be accompanied by a description or diagnosis in Latin or English, or reference to such, not in any language as before (Art. 36.3). An extensive revision of Art. 46 has clarified the situation in which "ex" may be used in the citation of authors' names and confirmed that the preposition "in", and what may follow, is bibliographic and not part of the author citation. One of the Permanent Committees listed in Div. II was abolished (the Committee for Hybrids) and one was renamed (the Committee for Fungi and Lichens, now Committee for Fungi).

From time to time Nomenclature Sections have accepted specific Examples ("voted Examples") in order to legislate nomenclatural practice where the corresponding Article of the Code is open to divergent interpretation or may not even cover the matter at all. One such Example, adopted by the Tokyo Congress, appears as Art. 8 Ex. 1, making clear what had hitherto been controversial, namely that "cultures permanently preserved in a metabolically inactive state" are to be considered "preserved permanently" (Art. 8.2), and, although in a sense "living plants or cultures", are eligible as types, regularizing a procedure adopted by yeast taxonomists in particular. Whereas the Editorial Committee normally has the power to delete, modify or add Examples in order to clarify the Code, this power does not extend to voted Examples, which the Editorial Committee is obligated to retain, whether or not they actually exemplify the rules. In response to a suggestion, made at the Yokohama meetings, that voted Examples should be clearly indicated, an asterisk (*) has been inserted against each one.

Although proposals made to the Tokyo Congress to provide for the granting of protection to names (or some aspect of names, e.g. types) on approved lists (the "NCU proposals") did not receive the 60 % majority necessary for their adoption, the Section was particularly impressed by the utility of the list of species names in Trichocomaceae (incl. Aspergillus and Penicillium) in ensuring nomenclatural stability in that group. Accordingly the Section adopted the following resolution that authorizes users of names in that family to suspend application of the Code where necessary: "The Nomenclature Section, noting that the 'List of Names in Current Use in the Trichocomaceae' (Regnum Veg. 128: 13-57. 1994) has already been approved by the International Commission on Penicillium and Aspergillus of the International Union of Microbiological Societies (IUMS), urges taxonomists not to adopt names that would compete with or change the application of any names on that list."

Apart from the addition of the new App. V referred to above, the Appendices remain those established in the Berlin Code. App. I deals with the naming of hybrids; App. IIA lists conserved names of families of algae, fungi, and pteridophytes, which are only conserved against listed rejected names, and App. IIB those of bryophytes and spermatophytes, which are conserved against all competing names not themselves included in the list; App. IIIA lists conserved generic names and the corresponding rejected names, and App. IIIB likewise for species names; App. IV lists names rejected under what is now Art. 56 (formerly Art. 69). Within these Appendices, some restructuring became necessary, partly because of the growing number of algal classes involved in conservation (two being added in this Code) and partly because of the present and foreseeable expansion of some of the smaller Appendices (IIIB and IV in particular). Six major groups are now recognized for the purposes of all these Appendices, and are designated by identical capital letters in each Appendix: A for algae, B for fungi, C for bryophytes, D for pteridophytes, E for spermatophytes, and F for fossil plants. In App. IIIA, subheadings with Arabic numerals are used for the algal and bryophyte classes. Under these headings and subheadings, conserved names are listed alphabetically, except in the case of genera of spermatophytes, for which the Dalla Torre & Harms numbering system and family definitions have been retained once more. It has been made explicit that, in App. III, all names of diatoms, whether with fossil or recent types and whether or not the genera include recent species, are listed under Bacillariophyceae rather than with the other fossil plants.

The procedures for producing this edition of the Code have followed the pattern outlined in Div. III of the Code and traditions well established since the Paris Congress of 1954. Published proposals for amendment, with comments by the Rapporteurs, were assembled in a "Synopsis of proposals" (Taxon 42: 191-271. 1993). Results of the Preliminary Mail Vote on these proposals, a strictly advisory but very helpful expression of opinion, were made available at registration for the Nomenclature Section of the Tokyo Congress, in the Congress Center of Pacifico, Yokohama, Japan. The Section met from 23 to 27 August, just before the regular sessions of the Congress, and acted on the 321 proposals before it, accepting some 82 and referring another 42 to the Editorial Committee for modification of the Code. The Section's decisions were sanctioned by resolution of the closing plenary session of the Congress on 3 September 1993 (see below) and became official at that time. A list of them appeared along with the results of the preliminary mail vote (in Taxon 42: 907-922. 1993). A preliminary transcript of the complete tape records of the nomenclature sessions, prepared by Fred Barrie, Werner Greuter, and John McNeill, was available to all members of the Editorial Committee at their meeting in January 1994. The full report of the Section's proceedings, including the essence of the debates and comments made during the deliberations, has since been published as a separate volume (Englera 14. 1994).

It is the duty of the Editorial Committee, elected by the Section (and, by tradition, from among those present for the discussions), to incorporate the decisions of the Congress into the Code and to make whatever strictly editorial changes are desirable for smooth, consistent, accurate, and clear reading. The composition of the Editorial Committee usually changes slightly at each Congress, and this was also the case on this occasion. Although the positions of Chairman and Secretary were unchanged in that Werner Greuter had continued as Rapporteur-général for the Tokyo Congress and John McNeill as Vice-rapporteur, the Committee lost three former members, Riclef Grolle, Frans Stafleu and Ed Voss, the two latter having served for several terms on the Editorial Committee. Frans Stafleu had been Vice-rapporteur and Secretary of the Editorial Committee from 1954 to 1964, Rapporteur-général and Chairman of the Committee from 1964 to 1979, and as President of the Nomenclature Section at Berlin in 1989 he had returned to the Committee for the preparation of the Berlin Code; while Ed Voss had served continuously on the Committee since 1964, being Vice-rapporteur and Secretary of the Committee from 1964 to 1979, Rapporteur-général and Chairman of the Committee for the 1981 Sydney Congress, and a member of the Committee for the Berlin Code. Although their experience was missed, the Committee was very well served by their replacements: Fred Barrie, Missouri Botanical Garden (currently on assignment at the Field Museum, Chicago); Per Magnus Jørgensen, University of Bergen; and Piers Trehane, Wimborne, Dorset, U.K. (co-opted to replace Alan Leslie, Royal Horticultural Society, Wisley, U.K., elected to the Committee in Yokohama but unable to serve); all of whom joined most effectively in the work of the Committee.

After circulation of a first draft of the text of the new Code, the Editorial Committee met at the "Botanischer Garten und Botanisches Museum Berlin-Dahlem" from 2-7 January 1994. All 11 members of the Committee were present for this traditional and essential meeting that explores as exhaustively as possible the clearest and most concise way to express in the Code the decisions of the Nomenclature Section. A myriad of editorial details must be addressed to ensure that the resulting work is unambiguous to all users, regardless of their primary language. The Editorial Committee recognizes that complete clarity and consistency are hardly achievable. Some instances of imprecise, conflicting, or otherwise unsatisfactory wording may still remain in the Code. Any effort to resolve certain points would result in extending the operation of the Code or restricting it, depending upon one's reading of the present text, and would not, therefore, be covered by the Editorial Committee's mandate.

The method by which some or all scientific names are set off in printed text varies substantially between different countries and language traditions. Perhaps as a result, there has been an unevenness in this regard in different editions of the Code. In an attempt to achieve uniformity, the Sydney Code and the Berlin Code italicized all scientific names at the rank of family and below, i.e. those for which priority is mandatory. The present Editorial Committee recognized that this policy was rather illogical, and, in the Tokyo Code, all scientific names falling under the provisions of the Code are italicized, whereas informal designations appear in Roman type. For example, in Art. 13.1 (d) the ordinal names Uredinales, Ustilaginales, etc. are italicized, whereas the informal group name "fungi" is not. The Editorial Committee considers this to be the most appropriate form of presentation in a code of nomenclature but does not aim to impose this as a standard to be followed in other publications, which may have different editorial traditions, often of long standing.

Consistency within the Code regarding bibliographic style and details, in a manner which is non-confusable and agreeable to all users, has been among our prime editorial concerns. Standardization aids are now available which did not exist years ago, providing an almost complete coverage of high standard for various categories of data. We have consistently used "TL-2" (Stafleu & Cowan, Taxonomic literature, ed. 2; with Suppl. 1 & 2, by Stafleu & Mennega) for book title abbreviations, "B-P-H" (Botanico-Periodicum-Huntianum) and its Supplement for the citation of journal titles, and Brummitt & Powell's Authors of plant names (Royal Botanic Gardens, Kew, 1992), for author citations. The style of citation used in the Names in Current Use (NCU) lists, and explained there in detail (see Regnum Veg. 126: 912. 1993), has been followed throughout. For the countless nomenclatural citations in the Appendices this standardization was a major undertaking. Whereas new-style entries were readily available for most of the conserved names of families (from Regnum Veg. 126) and genera (from Regnum Veg. 129), they had to be established anew for nomina rejicienda. Standardized author citations were introduced by Paul Kirk, International Mycological Institute, Egham, for all such names that had been downloaded from the Index nominum genericorum database by Ellen Farr, Smithsonian Institution, Washington - which were only those that are explicitly marked "nom. rej." in that database (perhaps slightly more than one half of the total). Norbert Kilian, Berlin, working under an IAPT contract, carried out all the remaining standardizations manually. Brigitte Zimmer, Berlin, did extensive consistency checks.

The updating of App. II-IV, meaning not only the additions and changes reflecting adopted proposals but also extensive verification of extant entries which in several cases resulted in substantial editorial corrections, was done in conjunction with experts acting either in their capacity of Editorial Committee members or Permanent Committee secretaries. Paul Silva took care of the algal entries; Vincent Demoulin, assisted by Walter Gams, of the fungal ones; Gea Zijlstra not only provided the bryophyte additions but also many updates and amendments resulting from her work with the Index nominum genericorum; Dan Nicolson prepared the additions for pteridophytes and spermatophytes, for the latter of which Dick Brummitt provided countless careful contributions; and Bill Chaloner took responsibility for fossil plants. The great and generous help of them all is gratefully acknowledged.

Whereas the index to App. III, completely computer-generated from its content, has not undergone any major change, the main index has been completely restructured and divided into two halves (scientific names and subject index) in an effort to make the content of the Code more readily accessible to teachers and students of botany as well as to those who apply the Code on a regular basis. This complete restructuring and rewriting, which we hope will be seen as a significant improvement on previous versions, was carried out by Piers Trehane. It proved to be a demanding and exhausting chore, for which he deserves all our gratitude.

The final editing of the whole text, including the Appendices and Indices, was undertaken by Werner Greuter in close contact with other members of the Editorial Committee, a circumstance made easier by the development of fax transmission and electronic communication. Brigitte Zimmer, assisted by Norbert Kilian for the Appendices portion, produced camera-ready copy of the text.

In addition to those who have helped produce this new edition of the Code, botanical nomenclature depends on the scores of botanists who serve on the Permanent Nomenclature Committees that work continuously between Congresses, dealing principally with proposals for conservation or rejection, and those others who are members of Special Committees, reviewing and seeking solutions to the problems assigned to them by the Nomenclature Section of the previous Congress. Botanical Nomenclature is remarkable for the large number of taxonomists who voluntarily work so effectively and for such long hours, to the immeasurable benefit of all their colleagues who must use plant names and on whose behalf this word of sincere thanks is expressed.

Ultimately, however, plant nomenclature is not governed by a bureaucracy of committees but, in an open and democratic manner, by the community of its users represented by the enrolled members of International Botanical Congresses. The user-driven process by which plant nomenclature is regulated is of utmost importance for a Code which, having no "teeth" in the way of penalties for infringements, entirely depends on user consensus for its universal application and implementation.

The International code of botanical nomenclature is therefore published under the ultimate authority of the International Botanical Congresses. The Tokyo Congress at its final plenary session adopted the following resolution relating to nomenclature:

"Considering the great importance of a stable system of scientific names of plants for use in the pure and applied sciences and in many other domains of public life and economy;

"noting with satisfaction recent important improvements in the International code of botanical nomenclature and ongoing efforts to explore new avenues for increased stability and security in the application of plant names;

"the XV International Botanical Congress urges plant taxonomists, while such work continues, to avoid displacing well established names for purely nomenclatural reasons, whether by change in their application or by resurrection of long-forgotten names;

"resolves that the decisions of the Nomenclature Section with respect to the International code of botanical nomenclature, as well as the appointment of officers and members of the nomenclature committees, made by that section during its meetings, 22-27 August, be accepted."

This resolution goes far beyond the traditional act of ratification of nomenclature actions and Permanent Committee nominations by Congress. By it, and through the International Union of Biological Sciences under whose auspices those Congresses are held, plant taxonomists are urged to become the champions of nomenclatural stability. Name changes made for purely nomenclatural reasons (as opposed to those that result from changing taxonomic concepts, hopefully reflecting a progress of our science) are to be avoided.

Does this mean that the present Code is a document of little consequence, to be set aside each time its application leads to results felt (by some) to be disagreeable? Certainly not. The Code now offers generous new ways to avoid nomenclatural changes by proposing the conservation or rejection of names, and these opportunities are to be used. Should these not suffice, new provisions may have to be devised and incorporated in the future.

The Code is a living and adapting body of law, and as long as it keeps evolving in tune with changing needs and new challenges it will keep its authority and strength. The Tokyo Code is, we believe, a significant landmark in this ongoing adaptive process.

May 1994Werner Greuter
John McNeill

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