In plant genetic resources, an early, cultivated form of a crop species, evolved from a wild population, and generally composed of a heterogeneous mixture of genotypes. It typically refers to a local variety of cannabis that has adapted to the environment of its geographic location. This accounts for genetic variation between landrace strains, which have been crossbred to produce the cannabis variety we see today. Landrace strains are often times named after their native region, like Afghani, Thai, and Hawaiian, and traces of landraces are sometimes detectable in the names of their crossbred descendants.
Merriam-Webster Online Dictionary
Landrace (noun) a swine of any of several breeds locally developed in northern Europe
Heirloom, Indigenous Strain, Native Variety, Traditional Cultivar, Local Breed