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Graft-chimaera

Image:+Laburnocytisus Wideangle.jpg is a spectacular example of a graft-chimaera]]

In horticulture, a graft-chimaera may arise in grafting at the point of contact between rootstock and scion and will have properties intermediate between those of its "parents". A graft-chimaera is not a true hybrid but a mixture of cells, each with the genotype of one of its "parents": it is a chimaera. Hence, the once widely used term "graft-hybrid" is not descriptive; it is now frowned upon.

Propagation is by cloning only. In practice graft-chimaeras are not noted for their stability and may easily revert to one of the "parents".

Nomenclature

Article 21 of the ICNCP stipulates that a graft-chimaera can be indicated either by

  • a formula: the names of both "parents", in alphabetical order, joined by the plus sign "+":

: Crataegus + Mespilus

  • a name:
  • if the "parents" belong to different genera a name may be formed by joining part of one generic name to the whole of the other generic name. This name must not be identical to a generic name published under the International Code of Nomenclature for algae, fungi, and plants (ICN). For example +{{nbsp}}Crataegomespilus is the name for the graft-chimaera which may also be indicated by the formula Crataegus + Mespilus. This name is clearly different from ×{{nbsp}}Crataemespilus, the name under the ICN for the true hybrid between Crataegus and Mespilus, which can also be designated by the formula Crataegus × Mespilus.{{efn|+{{nbsp}}Crataegomespilus is now considered a synonym for Crataegus.{{cite POWO |id=33738-1 |title=+ Crataegomespilus Simon-Louis ex Bellair |access-date=20 December 2023 }}}}
  • if both "parents" belong to the same genus the graft-chimaera may be given a cultivar name. For example Syringa 'Correlata' is a graft-chimaera involving Syringa vulgaris (common lilac) and Syringa × chinensis (Rouen lilac, which is itself a hybrid between S. vulgaris and S. persica). No plus sign is used, because both "parents" belong to the genus Syringa.

A graft-chimaera cannot have a species name, because it is simultaneously two species. Although +{{nbsp}}Laburnocytisus 'Adamii', for example, is sometimes seen written as if it were a species (+{{nbsp}}Laburnocytisus adamii), this is incorrect.{{fact|date=September 2020}}

In Darwin's works

Charles Darwin [http://www.darwin200.nl/vartn10h/chap11.html "The Variation of Animals and Plants Under Domestication"] {{Webarchive|url=https://web.archive.org/web/20090205034429/http://darwin200.nl/vartn10h/chap11.html |date=2009-02-05 }}, 1868 г.:

I will therefore give all the facts which I have been able to collect on the formation of hybrids between distinct species or varieties, without the intervention of the sexual organs. For if, as I am now convinced, this is possible, it is a most important fact, which will sooner or later change the views held by physiologists with respect to sexual reproduction. A sufficient body of facts will afterwards be adduced, showing that the segregation or separation of the characters of the two parent-forms by bud-variation, as in the case of Cytisus adami, is not an unusual though a striking phenomenon. We shall further see that a whole bud may thus revert, or only half, or some smaller segment.

Genera

The following graft-chimaera genera are accepted:{{cite web |url=http://www.plantsoftheworldonline.org |title=POWO |author= |date=2023 |website=Plants of the World Online |publisher=Royal Botanic Gardens, Kew |access-date=20 December 2023 }}

See also

Notes

{{Notelist}}

References

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Category:Botanical nomenclature