Grex (horticulture)

The termgrex(pluralgregesorgrexes;abbreviationgx), derived from theLatinnoungrex,gregis,meaning 'flock', has been expanded inbotanical nomenclatureto describe hybrids oforchids,based solely on their parentage.^[1]Grex names are one of the three categories of plant names governed by theInternational Code of Nomenclature for Cultivated Plants;within a grex thecultivar groupcategory can be used to refer to plants by their shared characteristics (rather than by their parentage), and individual orchid plants can be selected (and propagated) and named ascultivars.^[2]^[3]

Botanical nomenclature of hybrids[edit]

The horticultural nomenclature of grexes exists within the framework of the botanical nomenclature of hybrid plants. Interspecific hybrids occur in nature, and are treated under theInternational Code of Nomenclature for algae, fungi, and plantsasnothospecies,('notho' indicating hybrid). They can optionally be given Linneanbinomialswith a multiplication sign "×" before the species epithet^[4]for exampleCrataegus×media.An offspring of a nothospecies, either with a member of the same nothospecies or any of the parental species as the other parent, has the same nothospecific name. The nothospecific binomial is an alias for a list of the ancestral species, whether the ancestry is precisely known or not.

For example:

a hybrid betweenCattleya warscewicziiRchb.f. 1854andCattleya aureaLinden 1883can be calledCattleya×hardyanaSander 1883or simplyCattleya hardyana.An offspring of aCattleya×hardyanapollenizedby anotherCattleya×hardyanawould also be calledCattleya×hardyana.Cattleya×hardyanawould also be the name of an offspring of aCattleya×hardyanapollenized by either aCattleya warscewicziior aCattleya aurea,or an offspring of either aCattleya warscewicziior aCattleya aureapollenized by aCattleya×hardyana.
×Brassocattleyais a nothogenus including all hybrids betweenBrassavolaandCattleya.It includes the speciesBrassocattleya×arauji,also known simply asBrassocattleya arauji,which includes all hybrids betweenBrassavola tuberculataandCattleya forbesii.^[5]

An earlier term wasnothomorphfor subordinate taxa to nothospecies. Since the 1982 meeting of theInternational Botanical Congress,such subordinate taxa are consideredvarieties(nothovars).

Horticultural treatment[edit]

Because many interspecific (and even intergeneric) barriers to hybridization in the Orchidaceae are maintained in nature only by pollinator behavior, it is easy to produce complex interspecific and even intergeneric hybrid orchid seeds: all it takes is a human motivated to use a toothpick, and proper care of the mother plant as it develops a seed pod. Germinating the seeds and growing them to maturity is more difficult, however.

When a hybrid cross is made, all of the seedlings grown from the resulting seed pod are considered to be in the same grex. Any additional plants produced from the hybridization of the same two parents (members of the same species or greges as the original parents) also belong to the grex.Reciprocal crossesare included within the same grex.^[6]If two members of the same grex produce offspring, the offspring receive the same grex name as the parents.

If a parent of a grex becomes asynonym,any grex names that were established by specifying the synonym are not necessarily discarded; the grex name that was published first is used (theprinciple of priority).^[7]

All of the members of a specific grex may be loosely thought of as "sister plants", and just like the brothers and sisters of any family, may share many traits or look quite different from one another. This is due to the randomization of genes passed on to progeny duringsexual reproduction.The hybridizer who created a new grex normally chooses to register the grex with a registration authority, thus creating a new grex name, but there is no requirement to do this. Individual plants may be givencultivarnames to distinguish them from siblings in their grex. Cultivar names are usually given to superior plants with the expectation of propagating that plant; all genetically identical copies of a plant, regardless of method of propagation (divisions or clones) share a cultivar name.

Naming[edit]

Two named cultivars from the same grex

CymbidiumKirby Lesh 'Pink Ice'

CymbidiumKirby Lesh 'Lonsdale'

The rules for the naming of greges are defined by theInternational Code of Nomenclature for Cultivated Plants(ICNCP). The grex name differs from a species name in that the gregaric part of the name is capitalized, is not italicized, and may consist of more than one word (limited to 30 characters in total, excluding spaces).^[8] Furthermore, names of greges are to be in a living language rather than Latin.

For example: an artificially produced hybrid betweenCattleya warscewicziiandC. dowiana(orC. aurea,which the RHS, the international orchid hybrid registration authority, considers to be a synonym ofC. dowiana) is calledC.Hardyana (1896) gx.^[9]An artificially produced seedling that results from pollinating aC.Hardyana (1896) gx with anotherC.Hardyana (1896) gx is also aC.Hardyana (1896) gx.^{[citation needed]}However, the hybrid produced betweenCattleyaHardyana (1896) gx andC. dowianais notC.Hardyana (1896) gx, butC.Prince John gx.^[10]In summary:

C. warscewiczii×C. dowiana→C.Hardyana (1896) gx
C.Hardyana (1896) gx ×C. warscewiczii→C.Eleanor (1918) gx^[11]
C. dowiana×C.Hardyana (1896) gx →C.Prince John gx

Registration[edit]

When the name of a grex is first established, a description is required that specifies two particular parents, where each parent is specified either as aspecies(ornothospecies) or as a grex.^[12]The grex name then applies to allhybridsbetween those two parents. There is a permitted exception if the full name of one of the parents is known but the other is known only to genus level or nothogenus level.^[13]

New grex names are now established by theRoyal Horticultural Society,which receives applications from orchid hybridizers.^[14]^[15]

Relationship with nothospecies[edit]

The concept of grex and nothospecies are similar, but not equivalent. While greges are only used within the orchid family, nothospecies are used for any plant (including orchids).

Furthermore, a grex and nothospecies differ in that a grex and a nothospecies can have the same parentage, but are not equivalent because the nothospecies includes back-crosses and the grex does not.^[16]They can even have the sameepithet,distinguished by typography (seebotanical namefor explanation of epithets), although since January 2010 it is not permitted to publish such grex names if the nothospecies name already exists.^[16]

Hybrids between a grex and a species/nothospecies are named as greges, but this is not permitted if the nothospecies parent has the same parentage as the grex parent. That situation is a back-cross, and the nothospecies name is applied to the progeny.^[16]

References[edit]

^(Brickell et al. 2009,Article 4.1)
^(Brickell et al. 2009,p. x)
^HORTAX: Cultivated Plant Taxonomy Group,archived fromthe originalon 17 August 2016,retrieved30 July2016
^(McNeill et al. 2012,Article H1)
^World Checklist of Selected Plant Families,retrieved2 August2016^{[permanent dead link]}
^(Brickell et al. 2009,Article 4 Note 2)
^(Brickell et al. 2009,Article 4.3)
^(Brickell et al. 2009,Article 21.13)
^"CattleyaHardyana (1896) ".The International Orchid Register.Royal Horticultural Society.Retrieved2023-12-18.
^"CattleyaPrince John ".The International Orchid Register.Royal Horticultural Society.Retrieved2023-12-18.
^"CattleyaEleanor (1918) ".The International Orchid Register.Royal Horticultural Society.Retrieved2023-12-18.
^(Brickell et al. 2009,Article 4)
^(Brickell et al. 2009,Article 27.4)
^(Brickell et al. 2009,Appendix 1)
^Orchid hybrid registration,Royal Horticultural Society,retrieved3 August2016
^^a ^b ^c(Brickell et al. 2009,Article 23.5)

Bibliography[edit]

Brickell, C.D.; Alexander, C.; David, J.C.; Hetterscheid, W.L.A.; Leslie, A.C.; Malecot, V.; Jin, X.; Cubey, J.J. (2009),International Code of Nomenclature for Cultivated Plants (ICNCP or Cultivated Plant Code) incorporating the Rules and Recommendations for naming plants in cultivation, Eighth Edition, Adopted by the International Union of Biological Sciences International Commission for the Nomenclature of Cultivated Plants(PDF),International Association for Plant Taxonomy and International Society for Horticultural Science,ISBN 978-90-6605-662-6
McNeill, J.; Barrie, F.R.; Buck, W.R.; Demoulin, V.; Greuter, W.; Hawksworth, D.L.; Herendeen, P.S.; Knapp, S.; Marhold, K.; Prado, J.; Prud'homme Van Reine, W.F.; Smith, G.F.; Wiersema, J.H.; Turland, N.J. (2012),International Code of Nomenclature for algae, fungi, and plants (Melbourne Code) adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011,vol. Regnum Vegetabile 154, A.R.G. Gantner Verlag KG,ISBN 978-3-87429-425-6
RHS(2016)."Search The International Orchid Register".Royal Horticultural Society.Retrieved28 November2017.

External links[edit]

[1] (Brickell et al. 2009,Article 4.1)

[2] (Brickell et al. 2009,p. x)

[3] HORTAX: Cultivated Plant Taxonomy Group,archived fromthe originalon 17 August 2016,retrieved30 July2016

[4] (McNeill et al. 2012,Article H1)

[5] World Checklist of Selected Plant Families,retrieved2 August2016^{[permanent dead link]}

[6] (Brickell et al. 2009,Article 4 Note 2)

[7] (Brickell et al. 2009,Article 4.3)

[8] (Brickell et al. 2009,Article 21.13)

[9] "CattleyaHardyana (1896) ".The International Orchid Register.Royal Horticultural Society.Retrieved2023-12-18.

[10] "CattleyaPrince John ".The International Orchid Register.Royal Horticultural Society.Retrieved2023-12-18.

[11] "CattleyaEleanor (1918) ".The International Orchid Register.Royal Horticultural Society.Retrieved2023-12-18.

[12] (Brickell et al. 2009,Article 4)

[13] (Brickell et al. 2009,Article 27.4)

[14] (Brickell et al. 2009,Appendix 1)

[15] Orchid hybrid registration,Royal Horticultural Society,retrieved3 August2016

[B1-16] (Brickell et al. 2009,Article 23.5)

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