Question
Greetings Christopher:

This is more of a botany question that I'm curious about:  Why do most varieties of VFT have traps that change from green to red when they are in good growing conditions (especially 6+ hours of full sun each day)?  Is it a chlorophyll change brought on by extra UV radiation, or is it something more exotic?  Does the color red attract more food items into the traps for some reason?  Is the red portion inside the trap the only section that generates bug-attracting chemicals? How did botanists grow VFT varieties that are completely red (like the 'Red Dragon' variety)?  Why do a few VFT varieties not turn red in color no matter how good the growing conditions are?  Just some questions that I have rolling around in my head...  Thank you very much for your time in this matter, and I look forward to your reply! =)  

Best Regards,

Jennifer

Answer
Hello Jennifer,

The red pigment is just that, a pigmentation that is already found in Venus Flytraps that is expressed when there is enough sunlight to trigger it into expression. It is like melanin in human skin when we are in ultraviolet light. Venus Flytraps just use a different pigment, called anthocyanin, when the light is bright enough. This is generally considered a predatory evolutionary adaptation since it is the trap surface, the insides of the hinged trap leaves, that generally color up in the typical cultivar of Venus Flytraps. Since flies are a prime source of Flytrap prey, and flies are attracted to raw meat, it makes sense that the red wedges of trap leaves would attract flies looking for red chunks of raw meat to lay their eggs in.

This evolutionary adaptation is simply modified, like what happens with domestic animals when humans interfere with their natural processes, as growers simply look for plants that show expression of more or less coloration in bright sunlight and cross pollinate plants of similar color expression over and over until more or less coloration is eventually produced in their offspring over several generations. This is what occurred when domestic dogs were bred for size or strength or ferocity. All dog ancestors were wolves, but now we have Dachshunds that do not even resemble wolves at all. The same is occurring with Venus Flytraps with no pigment or all red pigment even on their petioles. A grower simply grew many hundreds of plants and kept only the ones that had more or less pigment each time and after many generations. Eventually they came up with plants with no red pigment, all red pigment, short teeth, saw edged teeth, double traps, extra large traps, fused edge traps, and others. My own Venus Flytraps have expressed a few traps with extra trigger hairs, red on the outside of the traps, and double teeth. If I wanted to, I could try to pollinate it with another plant with similar qualities in the hopes of producing and keeping only the offspring that showed double teeth or extra trigger hairs or even more red coloration outside the traps. Eventually I would have plants with those features most or all of the time instead of only some of the time.

I hope this helps you in understanding how Venus Flytrap pigmentation works and why some have more or less pigment. In any case, all green Flytraps do catch prey, but I do not know if they capture less prey than red Flytraps. Perhaps someone could do a study and experiment on this idea.

Christopher