Cyclamen Corolla: After Pollination

Fig. 1   Cyclamen flowers:  before and after pollination.

The cyclamen flower continues to amaze me.  In some of my previous blog posts, I described my observations on the movement of the petals (corolla) prior to fertilization and the eventual behavior of the seed head.  But the uniqueness of the plant has not ended there.  This beautiful plant is more mysterious than I originally thought. 

Fig. 2      Unfertilized flowers fade away.

 

Corolla of unfertilized flowers remains attached to the peduncle. 
It has been my recent observation that the corolla (petal) can fade away in two different manners depending on whether the flower is pollinated or not.  Firstly, flowers that have not been pollinated tend to senesce naturally while they remain attached to the peduncle.  The unpollinated flowers undergo a gradual decline of turgor resulting in wilting of the flowers (Fig.1).  This is then followed by a gradual discoloration of the corolla.  It is noteworthy that the corolla remains with the peduncle when pollination fails (Fig. 1).  The flower failed.

Fig. 3    After pollination flowers turn into seedheads. 

Pollination results in corolla abscission
Secondly, flowers that have been pollinated shed off their corolla shortly after fertilization has taken place (Fig. 2).  In other words pollination results in corolla abscission.  (Abscission is simply the natural separation of any plant part from the main plant system)  It has been established through research that there is a significant increase in ethylene levels on pollinated flowers as compared to the unpollinated ones.  Combine this thought with the common knowledge that ethylene causes abscission among others and we get an explanation for the abcission of the corolla in fertilized flowers.  The flower whose goal was to attract pollinator now enters a new stage - to support the developing embryo.  At this point, the corolla or petal has accomplished its purpose and is no longer necessary - it falls off the flower cleanly.

My "almost-scientific" personal opinion
When flowers begin to lose the flow of fluids and sugars from the main plant (Fig. 1) then how can one expect further production of plant hormones, such as ethylene, from these parts anymore?  So the idea that ethylene is the cause of corolla abscission is kind of counter-intuitive.  There are evidences that show the role of ethylene in the development of the embryo.  The separation of the corolla could be an incidental occurence as the sepals begin to push downward to enclose the recently fertilized ovary (Fig. 4).  In contrast, the unfertilized flower that has already lost its turgor (Fig. 2) no longer have the force to do anything - such as push the corolla off the flowers. 

Fig. 4   The sepal enclosing the fertilized ovary after pollination.

Every plant has a set of unique behaviors which the gardener, given enough time, eventually comes to notice and appreciate.

Cyclamen Exhibits Parental Instinct

Fig.1  The long flower stalks of cyclamen (Cyclamen persicum) curl downwards as the fruit develops.

About a year ago, I wrote something about the mystery of the cyclamen flower.  It has been my observation that the cyclamen flower is very fascinating.  At that time, I thought that the reflexing of the petals was all there was to it.   And yet as I continued to watch this plant I observe that the plant is in a serious business of ensuring a successful reproduction. Firstly,  all the petals reflex up when the flowers open to expose the androecium (pollen-producing parts) and gynoecium (ovule-producing parts). This is nature's way of promoting effective pollination.  Secondly, after pollination, the mystery continues as the plant tries to ensure that the seeds will eventually emerge into new plants.

Fig,. 2    The fruits are tucked under the leaves to mature.

Tucked Under the Leaves.  When pollination has occurred and petals have dropped, the long flower stalk arches down (Fig. 1) to an almost perfect circle (the fruit almost touching the base of the plant)(Fig.2) as if to hide the fruits safely under the leaves.  In the case of other species (Cyclamen coum, Cyclamen graecum, and Cyclamen rohltsianum), the stalks coil down.   The seeds under the leaves are protected from seed-eating birds or larger pests.   The foliage of the plant also provides a suitable microclimate for the seeds to grow.  Studies have shown that, there are three primary requirements for successful cyclamen seed germination: 1) absence of light; 2) adequate temperature; 3) constant water supply.  The thick and overlapping foliage of my plants inside pots provided all three requirements adequately as evidenced by the emergence seedlings (Fig. 3).

Fig.3    Cyclamen seedlings growing at the base of the plant.

New Life Begins.   At the base of the plant, the fruits matured and seeds dropped  as directed by nature.  When I saw seedlings growing under the leaves (Fig, 3) I was reminded of chicks taking refuge under the wings of the mother hen.

I am excited to have these seedlings and am curious to see what happens to them.   It is my intention to transplant some of them and leave some to grow where they are.    I wonder if these young seedlings are also equipped with yet another behavior that would allow them to make their way out from under the overlapping leaves of the mother plant.


Winter Plant.  At this time, my cyclamen plants are poised to bloom.  New flower buds are emerging like snake heads from the base of the plants (Fig. 3).  The patterned heart-shaped leaves (Fig.1) make the Cyclamen persicum an interesting plant even before the flowers come out. 

Cyclamen is not only an outstanding parent but also a striking winter and spring plant.

Mystery of the Cyclamen Flower

Most plants that have experienced the summer find rest in autumn as they follow a common earth-tone color.  Red, yellow, orange and brown are normal.  Then there are those radical plants that seem to rebel against this trend.  One unexpected colors of fall comes from the cyclamen flowers.  Not only do they provide a fresh shift from the "dying or resting theme" of those plants that have gone through the rigors of summer, they also provide a renewed crisp life of the season.  Since there are very few varieties of flowers in bloom, I had the luxury of observing this plant more closely than usual. 

Pendant-like blossoms.

The cyclamen flower starts in a droopy position with the end tip of the petals pointing downwards.  The petals are folded in a very organized manner and twisted tightly together forming a beautiful pendant that gracefully hangs on the long pedicel.

The petals turn upward, one at a time.  Flowers exhibiting this tendency are called "reflexed flowers". This phenomenon in directional growth of plant parts can be explained by a differential growth on the opposing surfaces any plant part.  In the case of the cyclamen flowers, growths on the opposite surfaces of the petal are not the same.  The inner surface undergoes a faster cell division or elongation than the other side. 

One petal turns upward at a time.

Reflexed Flower

Flowers are designed in such a way that they contribute to the success of reproduction.  The reflexed petals may seem to make pollination easier than in other plant species since the style is clearly sticking out as seen in the above picture.  One would wonder why seeds rarely form from cyclamen flowers without human intervention.  So I did a little bit of research and found a suitable explanation.  There is an evidence that the stigma is inside instead of the outside the style (Reinchardt S., Ewald F., Hellwig F.).  In normal flowers, the stigma is the sticky part of the flowers where pollen grains would stick to prior to its growth in the style during pollination.  In cyclamen, it is reversed - the style was shown to have a terminal aperture which closes at some point during anthesis thus limiting pollination time. The chemical that controls this opening and closing of the style is not determined at the present.

There's always something new to learn from the garden and cyclamen is indeed an interesting flower!

What's happening in your garden today?