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All components of the [plant] population are adapted to local climatic conditions, cultural practices, and disease and pests." Landrace plants are grown from seeds which have not been systematically selected and marketed by seed companies, nor developed by plant breeders.
The label landraces includes all those regional cultigens that are highly heterogeneous, but with enough characteristics in common to permit their recognition as a group.
Landraces are not all derived from ancient stock largely unmodified by human breeding interests.
In a number of cases, most commonly dogs and horses, domestic animals have escaped in sufficient numbers in an area to breed feral populations that, through evolutionary pressure, can form new landraces in only a few centuries.
Landraces are generally distinguished from cultivars, and from breeds in the standardized sense, although the term landrace breed is sometimes used as distinguished from the term standardized breed when referring to cattle.
For example, horse landraces are less common because human use of them for transport has meant that they have moved with people more commonly and constantly than most other domestic animals, reducing the incidence of populations locally genetically isolated for extensive periods of time.
and more clearly described (in Dutch) in 1909 by U. Mansholt, who wrote that landraces have better "stability of their characteristics" and "resistance capacity to tolerate adverse influences" but lower production capacity than cultivars, and are apt to change genetically when moved to another environment.
In 2005, a "working definition" of plant landraces was proposed: "a dynamic population(s) of a cultivated plant that has historical origin, distinct identity and lacks formal crop improvement, as well as often being genetically diverse, locally adapted and associated with traditional farming systems".
"Landrace populations are often highly variable in appearance, but they are each identifiable morphologically and have a certain genetic integrity. A landrace has particular properties or characteristics. Each has a reputation for adaptation to particular soil types according to the traditional peasant soil classifications, e.g.