Spontaneous somatic mutation and mutant cultivars.
Mutations are often called bud variations, bud mutations, somatic mutations, bud sports or briefly, sports.
Darwin (1868) defined bud variations as ‘all changes in structure or appearance which occasionally occur in full-grown plants in their flower-buds or leaf buds’ and in many cases ascribed these ‘changes’ to ‘spontaneous variability.’
source: Mutation Breeding: Theory and Practical Applications 1988
A. M. van Harten, Agricultural University, Wageningen, The Netherlands
A sudden variation in habit of growth or blossom color from the rest of the plant or others plants of its kind. Caused by a genetic change that may be accidental or spontaneous, or intentionally induced.
In botany, a sport or bud sport is a part of a plant that shows morphological differences from the rest of the plant. Sports may differ by foliage shape or color, flowers, or branch structure. Sports with desirable characteristics are often propagated vegetatively to form new cultivars that retain the characteristics of the new morphology.
See: Red Gravenstein. This variety is a sport (natural genetic mutation) of the Gravenstein apple.
Species: Malus domestica. Parentage: Sport of Gravenstein. Origin: Washington, United States.