horticulture Horticulture (from ) is the art and science of growing fruits, vegetables, flowers, trees, shrubs and ornamental plants. Horticulture is commonly associated with the more professional and technical aspects of plant cultivation on a smaller and mo ...

, a graft-chimaera may arise in

grafting Grafting or graftage is a horticulture, horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion () while the lower part is called the roots ...

at the point of contact between

rootstock A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced. It could also be described as a stem with a well developed root system, to which a bud from another plant is grafted. It can refer to ...

and

scion Scion may refer to: Horticulture *Scion (grafting), in horticulture, the upper part of a combined plant Arts, entertainment, and media Characters *Atlantean Scion, a device in the ''Tomb Raider'' video game series *Scion, avatar of the warrior en ...

and will have properties intermediate between those of its "parents". Unlike

graft hybrid Graft hybridisation refers to a form of asexual hybridisation where heritable modifications can be induced through grafting. Grafting joins plant parts, forming a genetically composite organism functioning as one plant. A scion is a shoot from one p ...

s, a graft-chimaera is not a true

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two diff ...

but a mixture of cells, each with the

genotype The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a ...

of one of its "parents": it is a

chimaera Chimaeras are Chondrichthyes, cartilaginous fish in the order (biology), order Chimaeriformes (), known informally as ghost sharks, rat fish (not to be confused with rattails), spookfish, or rabbit fish; the last two names are also applied to B ...

. Hence, the once widely used term "graft-hybrid" is inaccurate for a graft-chimaera. Propagation is by

cloning Cloning is the process of producing individual organisms with identical genomes, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction; this reproduction of an organism by itself without ...

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 The ''International Code of Nomenclature for Cultivated Plants'' (ICNCP) is a guide to the rules and regulations for naming cultigens, plants whose origin or selection is primarily due to intentional human activity. It is also known as Cultivate ...

'' 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 The plus sign () and the minus sign () are mathematical symbols used to denote positive and negative functions, respectively. In addition, the symbol represents the operation of addition, which results in a sum, while the symbol represents ...

"+": : ''Crataegus'' + ''Mespilus'' * a name: ** if the "parents" belong to different

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

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 The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN or ICNafp) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all tho ...

'' (''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''. ** if both "parents" belong to the same genus the graft-chimaera may be given a

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

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 In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

, 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 Darwi
"The Variation of Animals and Plants Under Domestication"
, 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: *'' + Arioechinopsis'' (''

Ariocarpus ''Ariocarpus'' is a small genus of succulent, subtropical plants of the family Cactaceae. It comes from limestone hills of Rio Grande in the south of Texas (''Ariocarpus fissuratus'') and also the north and the center of Mexico (all other speci ...

'' + ''

Echinopsis ''Echinopsis'' is a genus of Cactus, cacti native plant, native to South America, sometimes known as hedgehog cactus, sea-urchin cactus or Easter lily cactus. , there are about 20 accepted species, ranging from large and treelike types to small ...

'') *'' + Coryopuntia'' ('' Coryphantha'' + ''

Opuntia ''Opuntia'', commonly called the prickly pear cactus, is a genus of flowering plants in the cactus family Cactaceae, many known for their flavorful fruit and showy flowers. Cacti are native to the Americas, and are well adapted to arid clima ...

'') *'' + Echinastrophytum'' ('' Astrophytum'' + ''

Echinocactus ''Echinocactus'' is a genus of cacti in the subfamily Cactoideae. The generic name derives from the Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient w ...

'') *'' + Echinogymnocalycium'' (''Echinopsis'' + ''

Gymnocalycium ''Gymnocalycium'', commonly called chin cactus, is a genus of about 70 South American species of cactus. The genus name ''Gymnocalycium'' (from Greek, "naked calyx") refers to the flower buds bearing no hair or spines. In a 2023 classification of ...

'') *'' + Myrtigymnocalycium'' (''Gymnocalycium'' + '' Myrtillocactus'') *'' + Ortegopuntia'' (''Opuntia'' + '' Ortegocactus'') *'' + Pyrocydonia'' ('' Cydonia'' + ''

Pyrus Pears are fruits produced and consumed around the world, growing on a tree and harvested in late summer into mid-autumn. The pear tree and shrub are a species of genus ''Pyrus'' , in the family Rosaceae, bearing the pomaceous fruit of the sa ...

'') *'' + Uebelechinopsis'' (''Echinopsis'' + '' Uebelmannia'')

Notes

References

{{Reflist Botanical nomenclature

Nomenclature

In Darwin's works

Genera

See also

Notes

References