I planted yellow mums on each side of a gate of a picket fence along the side of my house. To the left and right of the yellow mums, I planted orange and maroon mums for a total of 10 plants. All were gifts so I do not know the source of the plants, e.g., nursery or cuttings from someone's own mum collection. The picture above was taken two years after I planted the mums. Notice the blooms of yellow mum on the right side of the gate, which have turned partially orange.
Below is a picture of the same plant two years later. The orange colored blooms have almost completely gobbled up the yellow mum.
Further down the row of mums, an orange mum is converting to yellow. Note in the picture that the yellow blooms are larger than the orange blooms.
Possible cause for flowers changing color
I contacted my County Extension Service (CES) for an explanation of this event, where flower color and even characteristics like bloom size where converting on my mum plants. The CES offered the possible cause of flowering color change as an instance called "sport." The best definition I found for sport comes from Wikipedia:
"In botany, a sport or bud sport is a part of a plant (normally a woody plant, but sometimes in herbs as well) 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. Such selections are often prone to "reversion", meaning that part or all of the plant reverts to its original form. An example of a bud sport is the nectarine, which developed from a bud sport from a peach."
What may have happened to my mum plants
The change in flower size and bloom color is a result of a genetic change in the plant. The changing mums may have been offspring from mum cuttings that had the genetic glitch. I have made a note in my garden journal to not take cuttings for rooting from the affected mum plants to avoid passing this generic makeup on to new mum plants.
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