Cultigen

Cultigen is a collective term for those plants that have been deliberately altered or selected by humans; they are man-made or anthropogenic plants. The following plants are cultigens:

• all plants with cultivar names - this comprises by far the greatest number of cultigens, ranging from selections of unusual minor plant variants and simple hybrids, to plants that are the result of highly sophisticated breeding and selection programs carried out over many years. Included here would be genetically modified plants (plants modified by the deliberate implantation of genetic material) and the namedgraft-chimaera (plants grafted to produce mixed tissue, the graft material possibly from wild plants, special selections, or hybrids)

• all anthropogenic plants that have not been given cultivar names - this would include unnamed (possibly rejected) plants that are the result of breeding and selection, and ancient cultigens - plants with binomials (i.e. without cultivar names) 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. Many of these ancient cultigens are precursors of important economic crops e.g. Zea mays

All plants in the above groupings remain cultigens when they are growing in the wild, whether they are naturalised or deliberately planted.

Formal definition

A cultigen is a plant whose origin or selection is primarily due to intentional human activity.

Origin of term

The word cultigen was coined in 1918 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 (ICBN).

In 1923 Bailey extended his original discussion pointing out that, at the rank of species, it was possible to distinguish two groups of plants, the cultigen and the indigen. He referred to indigens as:

those that are discovered in the wild

and cultigens as plants that:

arise in some way under the hand of man

He then defined a cultigen as:

... a species, or its equivalent, that has appeared under domestication ...

Cultigens and cultivars

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 . He defined cultivar in his 1923 paper as:

... a race subordinate to species, that has originated and persisted under cultivation; it is not necessarily, however, referable to a recognised botanical species. It is essentially the equivalent of the botanical variety except in respect to its origin.

This definition and understanding of cultivar has changed over time (see current definition in cultivar).

Cultigen 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 taxonomic (classification) category.

Usage

Bailey's last definition

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 as:

Plant or group known only in cultivation; presumably originating under domestication; contrast with indigen

This, in essence, is the definition given at the head of this piece.

Usage in botany

In botanical literature the word cultigen is used for plants that have been given binomials and are now known only in cultivation (as plants of unknown origin, generally presumed to be human selections) but there is no essential difference in principle between these ancient plants and modern plants altered by human activity that are named under the International Code of Nomenclature for Cultivated Plants (ICNCP). The use of a Latin binomial (only) for such plants seems misleading (even though it is permissible under the ICBN) because binomials are overwhelmingly used for “wild” plants, and cultivar names used for virtually all cultigens.

The use of cultigen in this botanical sense essentially follows Bailey's definition of cultigen given in 1923.

Usage in horticulture

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 which defines cultigen as:

A plant found only in cultivation or in the wild having escaped from cultivation; included here are many hybrids and cultivars,...

The use of cultigen in this sense is essentially the same as the last definition of the cultigen published by Bailey in 1924.

Other usage

The 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 . 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 "changed" in some way from its wild counterparts. 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.

Recommended usage

Wider use of the term cultigen as defined here has been proposed for the following reasons:

• supports the intent of Bailey's last definition of 1924
• assists clarity in non-technical discussions about “wild” and “cultivated” plants (for example, cultivated plants as commonly understood (plants in cultivation) are not the same as the "cultivated plants" of the ICNCP, and the distinction between "wild" and "cultivated" habitats is becoming progressively blurred)
• has the potential to simplify the language and definitions used in the Articles and Recommendations of the ICNCP
• gives greater precision and clarity to the definition of the respective scope, terminology and concepts of the International Code of Botanical Nomenclature (ICBN) and the International Code of Nomenclature for Cultivated Plants (ICNCP)
• avoids the potential for confusion within the ICNCP over its scope, that is, whether it is concerned with:
  • • where plants are growing (in the wild or in cultivation)
    • how they originated (whether they are the result of intentional human activity or not)
    • simply providing a mechanism for allocating names to those “cultivated” plants requiring special categories outside the Linnaean hierarchy of the ICBN .

Wild plants in cultivation

Many plants in cultivation are essentially the same as their wild counterparts and are therefore not cultigens. However,occasionally within natural plant variation there occur characters that are of value to horticulture but of little interest to botany. For example a plant might have flowers of several different colours but these may not have been given formal botanical names. It is customary in horticulture to introduce such variants to commerce and to give them cultivar names. Technically these plants have not been deliberately altered in any way from plants growing (or once growing) in the wild but as they are specially selected and named it seems permissable to refer to them as cultigens. However, these occurrences are few and account is taken of them in the formal definition of the cultigen given above although for clarity the reference to selection could mention that selection is for desirable attributes that are not recognised in botanical nomenclature (which excludes those plants simply transferred from the wild into cultivation).

Etymology: culti(vated) or culti(cultigen) + gen (gens Latin - kind)

See also Domestication of plants.

Further reading

Spencer, R.D. and Cross, R.G. 2007. The cultigen. Taxon 56(3):938-940

Spencer, R, Cross, R & Lumley, P. 2007. (3rd edn) Plant names: a guide to botanical nomenclature. CSIRO Publishing, Collingwood, Australia. (Also CABI International Wallingford, UK. The definition of cultigen given in the Glossary of this reference does not include deliberately selected plants that are identical to plants growing (or once growing) in the wild.

External Links

http://128.240.24.212/cgi-bin/omd?query=cultigen