Editing Cultivar (section)

== Different kinds ==

[[Image:Airport orchid.JPG|thumb|left|220px|{{center|A cultivar of the orchid genus ''[[Oncidium]]''}}]]

Which plants are chosen to be named as cultivars is simply a matter of convenience as the category was created to serve the practical needs of [[horticulture]], [[agricultural science|agriculture]], and [[forestry]].<ref>Cultivated Plant Code. Preamble & Principles {{Harvnb|Brickell|2009|p=19}}</ref>

Members of a particular cultivar are not necessarily genetically identical. The ''Cultivated Plant Code'' emphasizes that different cultivated plants may be accepted as different cultivars, even if they have the same genome, while cultivated plants with different genomes may be regarded as the same cultivar. The production of cultivars generally entails considerable human involvement although in a few cases it may be as little as simply selecting variation from plants growing in the wild (whether by collecting growing tissue to propagate from or by gathering seed).<ref>Cultivated Plant Code, Article 2.20 {{Harvnb|Brickell|2009|p=9}}</ref>

Cultivars generally occur as [[Ornamental plant|ornamentals]] and food crops: ''[[Malus]]'' '[[Granny Smith]]' and ''Malus'' '[[Red Delicious]]' are cultivars of apples propagated by cuttings or [[grafting]], ''[[Lactuca]]'' 'Red Sails' and ''Lactuca'' 'Great Lakes' are lettuce cultivars propagated by seeds. Named cultivars of ''[[Hosta]]'' and ''[[Hemerocallis]]'' plants are cultivars produced by [[micropropagation]] or division.<ref>{{Cite book |last=Armitage |first=Allan M. |url=https://books.google.com/books?id=kA6VgfxsstIC&pg=PA542 |title=Herbaceous Perennial Plants: A Treatise on their Identification, Culture, and Garden Attributes |date=2008-05-01 |publisher=Quarto Publishing Group USA |isbn=978-1-61058-380-0 |language=en}}</ref><ref>{{Cite book |last=Halevy |first=Abraham H. |url=https://books.google.com/books?id=9zSoDwAAQBAJ&pg=PA132 |title=Handbook of Flowering: Volume III |date=2019-07-23 |publisher=CRC Press |isbn=978-1-351-08100-9 |language=en}}</ref>

=== Clones ===

{{Main|Clone (botany)}}

[[File:Leucospermum cultivar Edit.jpg|right|thumb|220px|{{center|''[[Leucospermum]]'' 'Scarlet Ribbon'<br />A cross performed in Tasmania between ''[[Leucospermum glabrum|L.&nbsp;glabrum]]'' and ''[[Leucospermum tottum|L.&nbsp;tottum]]''}}]]

Cultivars that are produced asexually are genetically identical and known as [[Cloning|clones]]; this includes plants propagated by [[division (horticulture)|division]], [[layering]], [[cutting (plant)|cuttings]], [[grafting|grafts]], and [[budding]]. The propagating material may be taken from a particular part of the plant, such as a lateral branch, or from a particular phase of the life cycle, such as a juvenile leaf, or from aberrant growth as occurs with [[witch's broom]]. Plants whose distinctive characters are derived from the presence of an intracellular organism may also form a cultivar provided the characters are reproduced reliably from generation to generation. Plants of the same [[chimera (plant)|chimera]] (which have mutant tissues close to normal tissue) or graft-chimeras (which have vegetative tissue from different kinds of plants and which originate by grafting) may also constitute a cultivar.<ref>Cultivated Plant Code, Articles 2.5–2.11 {{Harvnb|Brickell|2009|pp=6–7}}</ref>

=== Seed-produced ===

Some cultivars "come true from seed", retaining their distinguishing characteristics when grown from seed. Such plants are termed a "variety", "selection", or "strain" but these are ambiguous and confusing words that are best avoided. In general, asexually propagated cultivars grown from seeds produce highly variable seedling plants, and should not be labelled with, or sold under, the parent cultivar's name.<ref>[http://www.rhs.org.uk/learning/publications/plantsman/0605/opinion.asp Courses / RHS Gardening<!-- Bot generated title -->] {{webarchive|url=https://web.archive.org/web/20051226124519/http://www.rhs.org.uk/learning/publications/plantsman/0605/opinion.asp |date=2005-12-26 }}</ref>

Seed-raised cultivars may be produced by uncontrolled pollination when characteristics that are distinct, uniform and stable are passed from parents to progeny. Some are produced as "lines" that are produced by repeated self-fertilisation or inbreeding or "multilines" that are made up of several closely related lines. Sometimes they are [[F1&nbsp;hybrid]]s which are the result of a deliberate repeatable single cross between two pure lines. A few F2 hybrid seed cultivars also exist, such as ''Achillea'' 'Summer Berries'.

Some cultivars are [[Agamospermy|agamospermous]] plants, which retain their genetic composition and characteristics under reproduction.<ref>Cultivated Plant Code, Articles 2.17–2.18 {{Harvnb|Brickell|2009|pp=7–8}}</ref> Occasionally cultivars are raised from seed of a specially selected provenance – for example the seed may be taken from plants that are resistant to a particular disease.<ref>Cultivated Plant Code, Articles 2.12–2.16  {{Harvnb|Brickell|2009|pp=7–8}}</ref>

=== Genetically modified ===

{{Main|Genetic engineering}}

Genetically modified plants with characteristics resulting from the deliberate implantation of genetic material from a different [[germplasm]] may form a cultivar. However, the [[International Code of Nomenclature for Cultivated Plants]] notes, "In practice such an assemblage is often marketed from one or more lines or multilines that have been genetically modified. These lines or multilines often remain in a constant state of development which makes the naming of such an assemblage as a cultivar a futile exercise."<ref>Cultivated Plant Code, Articles 2.19 {{Harvnb|Brickell|2009|pp=8–9}}</ref> However, retired transgenic varieties such as the [[fish tomato]], which are no longer being developed, do not run into this obstacle and can be given a cultivar name.

Cultivars may be selected because of a change in the [[ploidy]] level of a plant which may produce more desirable characteristics.<ref>{{Cite book |last=Lebot |first=Vincent |url=https://books.google.com/books?id=UInHDwAAQBAJ&pg=PA239 |title=Tropical Root and Tuber Crops, 2nd Edition |date=2019-12-02 |publisher=CABI |isbn=978-1-78924-336-9 |language=en}}</ref>