A naturally occurring genetic mutation, sometimes known as a sport or a break, causes a sudden change in the appearance of a plant. There are many ways this will show. You may notice coloured flecks in a white flower, or a perennial with single flowers might develop a stem that holds a double flower. Mutation can also cause a change in foliage colour or fruit appearance. Reversion is a form of plant mutation.

Generally, you may only notice one or two mutations on a plant, for example, there might be just one different coloured flower on a plant. Usually the plant will revert back to its original form the following year.

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.

The term chimera is used when genetically distinct tissues co-exist within the same plant or parts of a plant. For instance, some plants, such as chrysanthemums, roses and dahlias are prone to producing chimeral flowers, where the flowers have sectors of different colours, and chimeras are the usual basis for variegated plants.

Generally, genetic mutations are not a problem, and can be pruned out if undesirable; however, many sports will die out or revert back to their original form of their own accord.

Some sports are stable and may be of interest to nurseries who actively seek out new plants. Members of the RHS can contact RHS Gardening Advice to request a list of nurseries that advertise for new plants.