The small tree + Laburnocytisus 'Adamii' 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 + Crataegomespilus is the name for the graft-chimaera which may also be indicated by the formula Crataegus + Mespilus. This name is clearly different from × Crataemespilus, the name under the ICN for the true hybrid between Crataegus and Mespilus, which can also be designated by the formula Crataegus × Mespilus.[lower-alpha 1]
    • 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 + Laburnocytisus 'Adamii', for example, is sometimes seen written as if it were a species (+ Laburnocytisus adamii), this is incorrect.

In Darwin's works

Charles Darwin "The Variation of Animals and Plants Under Domestication" Archived 2009-02-05 at the Wayback Machine, 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:[2]

See also

Notes

  1. + Crataegomespilus is now considered a synonym for Crataegus.[1]

References

  1. "+ Crataegomespilus Simon-Louis ex Bellair". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 December 2023.
  2. "POWO". Plants of the World Online. Royal Botanic Gardens, Kew. 2023. Retrieved 20 December 2023.
  3. "+ Arioechinopsis Mottram". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 December 2023.
  4. "+ Coryopuntia Mottram". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 December 2023.
  5. "+ Echinastrophytum Mottram". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 December 2023.
  6. "+ Echinogymnocalycium Mottram". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 December 2023.
  7. "+ Myrtigymnocalycium Mottram". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 December 2023.
  8. "+ Ortegopuntia Tóth". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 December 2023.
  9. "+ Pyrocydonia Guillaumin". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 December 2023.
  10. "+ Uebelechinopsis G.D.Rowley". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 December 2023.
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