NOMENCLATURE OF CULTIVATED PLANTS: A HISTORICAL BOTANICAL STANDPOINT

Abstract

Prior to publication of the first edition of the International Code of Nomenclature of Cultivated Plants (ICNCP) some 50 years ago, the only rules governing the naming of cultivated plants were those that also dealt with plants in the wild, the forerunners of the present International Code of Botanical Nomenclature (ICBN). Even today, the Preamble to the ICBN states that its “rules and recommendations apply to all organisms traditionally treated as plants”, but also goes on to say that the ICNCP “deals with the use and formation of names for special plant categories in agricultural, forestry, and horticultural nomenclature.” The need for the ICNCP and the way in which the two Codes interact are addressed. The progressive independence of plant nomenclature from taxonomy, the theory and practice of classification, is outlined from Linnaeus’s development of the binomial to the adoption of the type method. In general, the ICBN makes no assumptions as to the methods, principles or purposes of taxonomy, save one, that the units of taxonomy, the taxa being named, are in some way nested in a hierarchy of ranks. Variation at and below the species level, whether in wild or cultivated plants, is not readily accommodated in a hierarchical structure. On the other hand, the need to communicate and hence name the enormous diversity of cultivated plants at such levels is manifest. The ICNCP provides the rules by which this can be achieved. Cultivated plants fall under the provisions of the ICBN in so far, but only in so far, as they fall within the general system of classification of plants; beyond that the provisions of the ICNCP, which do not require an extensive and obligatory hierarchy of entities, and do not presume that desirable groupings are necessarily non-overlapping, apply. INTRODUCTION As explained by Piers Trehane in the previous paper (Trehane, 2004), separate rules for the naming of cultivated plants are a relatively recent development, going back only some 50 years. Prior to publication of the first edition of the International Code of Nomenclature of Cultivated Plants in 1953 (Stearn, 1953), the only rules governing the naming of cultivated plants were those that also dealt with plants in the wild, i.e., the successive editions of the International Rules of Botanical Nomenclature (Briquet, 1906; 1912; 1935) (or the International Code of Botanical Nomenclature as it became in 1952 – Lanjouw et al., 1952), and their predecessors, such as Alphonse de Candolle’s Lois (Candolle, 1867). Art. 40 of the Lois dealt with the names of plants of horticultural origin and read (English translation, Candolle, 1868): “Seedlings, half-breeds of uncertain origin, and sports should receive from horticulturists fancy names in common language, as distinct as possible from the Latin names of species or varieties. When they can be traced back to a botanical species, subspecies, or variety, this is indicated by a succession of names (Pelargonium zonale, Mrs. Pollock).” This provision survived substantially unchanged as Art. 35 in all three official editions of the International Rules of Botanical Nomenclature (Briquet, 1906; 1912; 1935). Interestingly at the VI International Botanical Congress in Amsterdam in 1935, this Article was amended by adding the requirement: “Fancy epithets will be preceded by the letter ‘c’”, presaging the recognition of the “cultivar” (Camp et al., 1947; Sprague, 1950). (For a fuller history of the roots of the ICNCP in the rules of botanical nomenclature see Stearn (1952, 1953) and for a more Proc. XXVI IHC – IVth Int. Symp. Taxonomy of Cultivated Plants Ed. C.G. Davidson and P. Trehane Acta Hort. 634, ISHS 2004 Publication supported by Can. Int. Dev. Agency (CIDA) 30 radical view on the history of cultivated plant classification and nomenclature, see Hetterscheid et al. (1996)). The naming of cultivated plants goes back, however, to the very beginnings of binary nomenclature, to Linnaeus’s Species Plantarum in 1753 (Linnaeus, 1753), where, for example, some of our modern brassica crops can be distinguished as named variants of Brassica oleracea, each prefixed by a Greek letter, since 1981 treated formally as botanical varieties (i.e., in the rank varietas), cf. ICBN Art. 35.4 (Greuter et al., 2000). INDEPENDENCE OF NOMENCLATURE AND TAXONOMY In nomenclatural terms, Linnaeus’s great achievement was to provide a mechanism for the separation of the name of a species from the characters distinguishing it from its congeners. This arose through his invention of the one-word specific epithet, which, with the generic name, provided Linnaeus’s “nomen triviale” that we now consider the scientific name of a species, as opposed to the “nomen specificum legitimum” of Linnaeus and previous botanists that enumerated the diagnostic features of each species. This represents the first and vitally important step in separating nomenclature from taxonomy, separating the names applied to plants from the process of classifying them, because, prior to that, whenever a species was added to a genus, the nomen specificum legitimum, providing the diagnostic characters of the species, would in all probability also change. The mid-19th century saw the first codifications of rules of biological nomenclature, that for plants being enshrined in the Candolle’s Lois referred to above (Candolle, 1867). The principle of priority of publication as the criterion for choosing between competing names for the same taxonomic group (taxon) dates to that time. The second important step in separating plant nomenclature from plant taxonomy came with the development of the type method for determining the application of a name. This had a chequered history in botany, with its adoption by botanists in the United States (in the American Code – Arthur et al., 1907) long before its acceptance by the international community as a whole. This only came about in 1930 at the V International Botanical Congress in Cambridge, England, with the completion of the rapprochement between the International Rules and the American Code (Briquet, 1931; 1935) begun at the IV International Botanical Congress in Ithaca, New York, in 1926 (Duggar, 1929 2:1413-1597,1781-1782). The type method meant that the name of a taxon became substantially independent of its circumscription. The name became fixed to a reference point, the type, and, so long as that element remained within the taxon, its name was retained, even with substantial changes in circumscription. Of course, when two or more taxa are combined, and the types of more than one name fall within the circumscription of the combined taxon, the principles of priority of publication of the names involved applies. I discuss this not to bore you with a long history of botanical nomenclature – I would refer those who are interested to the excellent account by Nicolson (1991) – but to emphasize that biological nomenclature (for the same processes have occurred in zoology) seeks to be as independent as possible of the theory and practice of taxonomy – of the processes of classification. Indeed in its Preamble, the current edition of the International Code of Zoological Nomenclature (Ride et al., 1999) states that “none [of its provisions] restricts taxonomic thought or actions”. The success of our rules of nomenclature in doing this is well illustrated by the fact that the current system of scientific nomenclature in biology was developed under a paradigm of special creation, survived the Darwinian revolution intact, was unaffected by the conflicts of pheneticists, eclecticists and cladists in the 1960’s and 1970’s, and remains, 250 years after its origin, the universal mechanism for communication about the products of biodiversity. Even the current PhyloCode initiative (Cantino and De Queiroz, 2000), although with broader goals, is focused on communication at the level of major evolutionary lineages, not at that of genera and species, and, moreover, is an initiative that fails to appreciate the flexibility and capability of the existing system, so-called “Linnaean nomenclature” (cf. Kress, 2002).