Sometimes plants may mutate. The likelyhood of this happening is greater with hybrids. Practically all mums today are hybrids.

In nature, strains have been refined by centuries of inbreeding and this is why a yellow dandelion will produce yellow dandelion offspring (or in my yard: MANY yellow dandelion offspring).

Hybridizers (aka gardeners with too much free time) will then try to breed two related flowers to create new types, to improve growth habit, height, flower color,etc. When they succeed they market a new product such as a new chrysanthemum with yellow flowers.

However, the strains in the plant are no longer inbreed through generations. By crossing with other (related) plants, the grower has introduced a lot of variability into the gene pool and this means that the result is no longer predictable.

e.g. compare it to this:
- a group of people which has been isloated for ages (eskimoes, for example) are "discovered" by explorers. All children of these eskimoes look similar (not exactly like, but similar) to their parents. Now, the chief's daughter falls in love with a hansome guy from NC, and other people in the group marries outside their clan, too. Eventually, the kids will no longer look similar to their original ancestors. New variability has been introduced into the gene pool and the result is "no longer predictable".

The child of two different groups of people we call inter-racial children. In biology, when referring to animals and plants, they are termed "hybrids".

A popular definition is that the offspring of two unrelated specimen produces a new, different, improved specimen.

Unlike humans, plants also propagate by vegetative means (e.g. by spreading through offsets or runners for example). These offsets are what you notice as "having to divide the clump every few years". Some of these offsets may have mutated.

The mutation when it happens in nature without help from hybridizers is called a "SPORT".

Sporting is quite common in some plants, and more rare in others. But sporting is a lot more common in heavily hybridized plants compared to plants which are very "pure" (from the point of view of having been inbred for centuries).

May I recommend the article below:

Here is a link that might be useful: Understanding hybrids

to add to above : mutations can occur if your plants have received a chemical treatment (insecticides, paint, etc.)...
Also ; you mention A bloom ; is that one single bloom amongst the other yellows or did they all turn marron? It could be (stress could) that at the time when you planted your mums there was a tiny seedling inthe pot that got transplanted and now is flowering?

Thank you kdjoergensen. Your eskimo analogy put in perspective for me. I do wonder if hybrids are usually marked as such. I appreciate the hybrid/mutation lesson. I will be more observant of the plants I get from now on. Thanks again
Angie

Nazanine,
No chemicals! This bloom is the only one, and it is earlier than I usually see them. Not sure of the seed idea, since it was a division off of an older plant. I will be more observant of them when the rest start blooming. Thanks for your input!
Angie

I was wondering if you ever found out why your mums changed colors? I have several that were here when we moved into our house and I know for a fact (I have photos) that a few of mine came up this year and the blooms were a totally different color than last year. I was wondering if it had to do with the soil acidity or fertilizing? Any info would be appreciated

okmissouri, All of my divisions from the original plant are blooming...and they are the purple color, not the pale yellow. Now the "momma" plant is fixing to bloom, but I can't tell what color it is yet....The best I can figure is the plant is hybrid, and reverting to some other genetic DNA. kdjoergensen put up a good link for me, it might help you. I sure don't fertilize, and don't know much about my soil acidity. Good luck!

Very good analysis,kdjoergensen.
Now let me ask out of curiousity: Do plants like MUMS selfhybridize or do their flowers change color due to weather conditions,sun light or some chemical like florigen ?

chiman

I recently read an article (no longer have it) where they were trying to get blue roses by indroducing human liver genes into it. The plant would have the gene but any seed produce would not have it (ie: must reproduce aesexually by cuttings to maintain the "blue" gene) I don't know much about plant biology (alas, a science graduate who never took plant biology / botany courses) so I don't know if they do the same thing with mums to produce certain colors - if so, it may be seedlings of the original plant that failed to carry the introduced color gene.

chaman, I don't know enough about mums to say if the flowers change colors with environmental conditions, but as long as you plant several hybridized plants in a close proximity of each other, the bees will do the crossing for you. Even the flowers on the same plant can be crossed and create new varities.

You really have to have very original species plants for this not to happen. E.g. take a walk in a nature setting and look at the field of red poppies. They will likely come true from type due to a) being genetically "pure" and b) no other types of poppies near by. Then compare a regular garden where you are almost certain to have highly hybridized plants and close.

Today, unless you make a special effort to avoid hybridized plants, chances are that any plant you are growing probably is a hybrid.

Kdjoergensen and Nazanine offer good ideas on this subject. Here is another thought. In garden plants, mutations are selected and propagated vegetatively. The yellow-flowered mum may have been a mutation found on a maroon-flowered mum. If additional maroon-flowered shoots appear over time, this is almost certainly the case. It is not unusual for a vegetatively propagated selection to spontaneously produce branches of its original form. I suspect that this is due to several causes: instability of the mutation, the retention of a small bit of original tissue (chimeral) in the selection, and additional mutations.
I'm not sure I understand the assertion that hybrids are more likely to produce mutations. The seedling groups of generations that follow will be more variable but I do not think the rate of mutations increases.

An orange tall bearded iris my aunt grew for years eventually reverted to yellow, starting with part of the clump(s). I have seen other examples of this kind of thing. I think this is the explanation for your chrysanthemum, it's an unstable selection that is reverting to purple.