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Name: Ginnie Gale
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What causes a Morning Glory flower to open in the AM ? Also, what makes the Morning Glory flower turn purple only on cool days? On hot and bright days mine stay a bright blue.

Thanks for your questions. As far as the Morning Glory flower goes, its 'purpose' in life is plant reproduction. With that 'goal', you can see how the flower would need to be open in the daytime when most of the likely insect pollinators would be visiting the flowers. You can see how the plant has evolved with this feature being important. Another way to look at it is in view of natural selection, where those plants whose flowers happen to be open in the daytime get pollinated and are therefore 'successful' in survival. Those plants whose genes perhaps directed 'late-night' flower opening were rarely if at all pollinated and did not therefore survive to the present day. As far as the actual opening process, it is most likely directed by sunlight and rising temperature directing an increase of water supply to the flower...causing it to unfurl. At nighttime the reverse happens and the flower closes. Some species remain open all night...these might actually attract night pollinators or perhaps have not yet evolved specialized mechanisms to open/close in day/night. As far as the color change goes, again, I suspect there is some 'motive' to the plant's coloration. Perhaps the insects early in the day are attracted to a particular hue, and the plant has evolved to make this color pre- dominate in the morning. Later afternoon insects might notice a differ- ant hue and the plant has also 'learned' this by natural selection. The mechanism again would be chemical in nature. Frequently chemicals of coloration are faded or altered by exposure to sunlight as they break down. You can see this yourself in old color photographs. Therefore I suspect that the chemicals produced by the plant in the morning for coloration age along with the flower and by nighttime, assuming the job of pollination is done, those components of the flower which can be reabsorbed by the plant are taken back by the plant and the extraneous part of the flower is shed. Naturally the plant will continue to hold the fertilized (pollinated) ovary to produce seeds.

One final interesting note....some of the plants produced by man in laboratories for special characteristics are sterile, that is, they go through the whole pollination process but they are not fertile and pollination will not produce viable seeds. I hope this information answers your questions. Thanks for using NEWTON.

Ric (rickru)

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