A cultivar is a strain of a plant that has been developed through cultivation. It is not a new species, but it has some distinctive traits that set it aside from other plants in the same species. Cultivars are only seen in cultivation and they must be maintained by gardeners. For many plants grown by humans, there are numerous strains within each species that have been developed to bring out specific desirable traits.
When naming a cultivar, people use the format Genus species 'Cultivar Name.' Single quotes are used around the name of the cultivar and it is usually presented in a vernacular, like Malus domesticus 'Granny Smith,' in the case of a popular apple cultivar. Sometimes, the genus name alone is used if the meaning will be clearly understood. The name is usually given by the person who bred that particular strain, and may be copyrighted in the case of commercially developed plants.
This term is a portmanteau of “cultivated variety.” Gardeners have been developing cultivars for centuries, selecting and carefully breeding plants to bring out traits ranging from variegated flowers to uniformly sized fruits. The careful breeding and rebreeding results in a plant with a series of stable and predictable traits that can be maintained through continued cultivation. When cultivars are crossed with each other, the result can be variable, depending on the dominance of different traits.
Gardeners can use seeds, cuttings, and bulbs in their development of new cultivars. The process starts with listing the desired traits, selecting specimens that exhibit these traits, and breeding until the traits express reliably. Cultivars are often named after their appearance, although they may also be given fanciful names that reference the region a strain was developed in or the name of the gardener who developed it.
Commercially bred plants may be legally protected with copyrights and other registrations. The firm that develops such plants can develop cultivars that cannot be used to cultivate new plants, such as flowers that do not go to seed or produce sterile seeds, obliging gardeners to purchase plants through them.
People interact with different cultivars on a regular basis. The assortment of potatoes in the produce section of a supermarket is a good example of an array of cultivars. Potatoes have been bred for traits such as size, appearance, and texture, with some cultivars being waxy while others are mealy. Likewise, many grocery stores feature several types of tomatoes, an array of apples, and a myriad of lettuces.