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A cultigen (from the Latin cultus - cultivated, and gens - kind) is a plant that has been deliberately altered or selected by humans; it is the result of artificial selection. These "man-made" or anthropogenic plants are, for the most part, plants of commerce that are used in horticulture, agriculture and forestry. Because cultigens are defined by their mode of origin and not by where they are growing, plants meeting this definition remain cultigens whether they are naturalised in the wild, deliberately planted in the wild, or growing in cultivation.
Cultigens arise in the following ways: selections of variants from the wild or cultivation including vegetative sports (aberrant growth that can be reproduced reliably in cultivation); plants that are the result of plant breeding and selection programs; genetically modified plants (plants modified by the deliberate implantation of genetic material); and graft-chimaeras (plants grafted to produce mixed tissue, the graft material possibly from wild plants, special selections, or hybrids). The study of cultigen nomenclature and classification forms the basis of cultivated plant taxonomy. Cultigens are scientifically named according to the principles, rules and recommendations laid down in the International Code of Nomenclature for Cultivated Plants (generally referred to as the Cultivated Plant Code).[1] The Cultivated Plant Code provides for the names of cultigens in three classification categories, the cultivar, the Group (formerly Cultivar-group), and the [[grex];[nb 1] it does not recognize the use of trade designations and other marketing devices as scientifically acceptable names.[2] Some cultigens have not been given cultivar names and these include: unnamed plants that are the result of breeding, selection, and tissue grafting; ancient cultigens - plants with binomials (i.e. recognized at the level of species) that occur in the wild but which have undergone selection and distribution by humans for so long that their original ancestral distributions and forms in the wild are uncertain or unknown - for example many ancient cultigens, like maize (Zea mays) and banana (Musa spp.), are precursors of important economic crops; and (presumed) anthropogenic plants that are no longer known in the wild and have not been given cultivar or Group names.
[edit] Formal definitionA cultigen is a plant whose origin or selection is primarily due to intentional human activity.[3] [edit] The distinction "wild" and "cultivated"Interest in the distinction between wild and cultivated plants dates back to antiquity. Botanical historian Alan Morton notes that wild and cultivated plants (cultigens) were of intense interest to the ancient Greek botanists (partly for religious reasons) and that the distinction was discussed in some detail by Theophrastus (370–285 BCE) the "Father of Botany". Theophrastus was a pupil of Aristotle and succeeded him as head of the Peripatetic School of Philosophy at the Lyceum in Athens. Theophrastus accepted the view that it was human action not divine intervention that produced cultivated plants (cultigens) from wild plants and he also "had an inkling of the limits of culturally induced (phenotypic) changes and of the importance of genetic constitution" (Historia Plantarum III, 2,2 and Causa Plantarum I, 9,3). He also noted that cultivated varieties of fruit trees would degenerate if cultivated from seed.[4] [edit] Origin of term The word cultigen was coined in 1918[5] by American Liberty Hyde Bailey (1858-1954) an American horticulturist, botanist and cofounder of the American Society for Horticultural Science. He was aware of the need for special categories for those cultivated plants that had arisen by intentional human activity and which would not fit neatly into the Linnaean hierarchical classification of ranks used by the International Code of Botanical Nomenclature (Cultivated Plant Code). In his 1918 paper Bailey noted that for anyone preparing a descriptive account of the cultivated plants of a country (he was at that time preparing such an account for North America) it would be clear that there are two gentes or kinds (Latin singular, gens; plural, gentes) of plants. Firstly, those that are of known origin or nativity "of known habitat". These he referred to as indigens. The other kind was:
He called this second kind of plant a cultigen, the word derived from the conflation of the Latin cultus - cultivated, and gens - kind. In 1923 [6] Bailey extended his original discussion emphasising that he was dealing with plants at the rank of species and he referred to indigens as:
and cultigens as plants that:
He then defined a cultigen as:
[edit] Bailey's definitions
Bailey soon altered his 1923 definition of cultigen when, in 1924, he gave a new definition in the Glossary of his Manual of Cultivated Plants[7] as:
This, in essence, is the definition given at the head of this piece. This definition of the cultigen permits the recognition of cultivars, unlike the 1923 definition which restricts the idea of the cultigen to plants at the rank of species. In later publications of the Liberty Hyde Bailey Hortorium, Cornell, the idea of the cultigen having the rank of species returned (e.g. Hortus Second in 1941 and Hortus Third in 1976): [8][9] both of these publications indicate that the terms cultigen and cultivar are not synonymous and that cultigens exist at the rank of species only.
Recent usage in horticulture has, however, maintained a distinction between cultigen and cultivar while nevertheless allowing the inclusion of cultivars within the definition (see "Usage in horticulture" below). [edit] Cultigens and cultivarsCultigen and cultivar may be confused with one-another. Cultigen is a general-purpose term encompassing not only plants with cultivar names but others as well (see introductory text above), while cultivar is a formal classification category (in the ICNCP). Although in his 1923 paper Bailey used only the rank of species for the cultigen, it was clear to him that many domesticated plants were more like botanical varieties than species and so he established a new classification category for these, the cultivar, generally assumed to be a contraction of the words “cultivated” and “variety”. Bailey was never explicit about the etymology of the word cultivar and it has been suggested that it is a contraction of the words “cultigen” and “variety” which seems more appropriate [10]. He defined cultivar in his 1923 paper as:
This definition and understanding of cultivar has changed over time (see current definition in cultivar). [edit] Usage[edit] Usage in botanyIn botanical literature the word cultigen is generally used to denote a plant which, like the wheat (Triticum aestivum) is of unknown origin, but presumed to be an ancient human selection. Plants like these have been given binomials according to the Botanical Code and therefore have names that have the same form as those of plants that occur naturally in the wild. As these cultigens are the result of deliberate human selection there is no difference, in principle, between them and modern plants with additional names under the Cultivated Plant Code. The use of binomials for cultigens occurs for the most part because they were following the accepted nomenclatural conventions that pre-dated the Cultivated Plant Code. In theory cultigens can be named under either Code or both, although in practice almost all have cultivar names governed by the Cultivated Plant Code. [edit] Usage in horticulture
The year 1953 was an important one for cultivated plant taxonomy because this was the date of publication of the first International Code of Nomenclature for Cultivated Plants in which Bailey’s term cultivar was introduced. It was also the year that the eponymous journal commemorating the work of Bailey (who died in 1954), Baileya, was published. In the first volume of Baileya taxonomist and colleague of Bailey, George Lawrence, wrote a short article clarifying the distinction between the new term cultivar and the variety. In the same article he also tried to clarify the critical term taxon which had been introduced by German biologist Meyer in the 1920s but had only just been introduced and accepted in botanical circles. This brief article by Lawrence is useful for its insight into the understanding of the meaning of the word cultigen at this time. He opens the article:
In horticulture the definition and use of the term cultigen has varied but generally, unlike usage in botany, it encompasses cultivars. One example is the definition given in the Botanical Glossary of The New Royal Horticultural Society Dictionary of Gardening[12] which defines cultigen as:
The use of cultigen in this sense is essentially the same as the definition of the cultigen published by Bailey in 1924. [edit] Other usageThe term cultigen is occasionally applied in a very general sense to any organisms that do not have a wild or uncultivated counterpart, see for example [13]. Animal breeds raised in captivity would be included here. It might seem that the word "domesticate" could serve the same purpose as cultigen. However, the widely held view that domesticated plants and animals are simply wild plants and animals used in domestic situations (often as tamed wild animals, or plants introduced directly from the wild, rather than being specially selected for particular desirable characteristics) would not support this view. However there is debate about what constitutes domestication and some authors maintain that to be termed domesticated or a "domesticate" a plant or animal must have been genetically "changed" in some way from its wild counterparts, either by conscious or unconscious selection.[14] Regardless of this debate, it is clear that the term cultigen originated within horticulture and botany and that these areas are where it has mostly been applied. [edit] Recommended usageWider use of the term cultigen as defined here has been proposed [3] for the following reasons:
[edit] Critique of definition
Potential misunderstandings and questions arising from the definition of cultigen given here have been discussed in the literature[15] and are summarised below.
[edit] See also[edit] References
[edit] Footnotes
[edit] Further reading
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