RHS on mutations (sports):
"Most mutations are random and are a result of a change within the cells of the plant, but mutations can sometimes be triggered by cold weather, temperature fluctuations or insect damage.
Sometimes the mutation is unnoticeable because the characteristics are not passed on from the cell where they occurred, but if the mutation occurs at the growing point, entire shoots can be affected as that cell multiplies and gives rise to whole cell lines."
Gardening Know how:
"A sport in the plant world is a genetic mutation that results from a faulty chromosomal replication. The results of the mutation are a segment of the plant that is distinctly different from the parent plant in both appearance (phenotype) and genetics (genotype). The genetic change is not a result of unusual growing conditions; it is an accident, a mutation. In many cases the new trait can be handed down to the organism's offspring."
