Nepenthes flower color alteration

[F R e N c H 3 z]

I was collecting some pollen on a Nepenthes truncata and was examining the flower stalk when I noticed some peculiar color alterations. The color alteration I am referring to occurred on the flower stalks of the raceme is very abrupt and distinctive. At first I thought that an area of the flower was receiving more light but this was not the case as the immediate flower over lacks complete red pigment. Then I thought maybe that it was an indication of flower age but I found both colors on various stages of flower development. Is this a case of gene expression at work (anthocyanins) or something else?

Sorry for the poor quality pictures, I was unable to get decent macro shots with my phone.

Edited February 16, 2011 by F R e N c H 3 z

[Chooka]

Hi FReNcH3z,

I am guessing it is some sort of signal to attract whatever the native pollen vectors are in the wild, highlighting ripe anthers.

As an aside, Nepenthes do not have anthocyanins. Being members of the order Caryophyllales, the red and yellow pigments of Nepenthes are Betalains (Betacyanins and Betaxanthins, respectively). Betalains have also been found in Drosera, and I suspect they are present in Dionaea as well. The presence of these pigments is one of the molecular links between Nepenthes and other plants such as cacti and the common beet. Anthocyanins have not been found in plants with Betalains.

Cheers,

Chooka

[F R e N c H 3 z]

Thanks Chooka,

I was really hoping to get an informative response like that! I had no idea anthocyanins were absent in Caryophyllales.

I guess one way to test that hypothesis would be to keep track of development on a few flowers and see whether color change occurs or not over their lifetime. Out of curiosity, have you seen this on any of your Nepenthes?

[Chooka]

Hey FReNcH3z,

I have noticed this sort of reddening in some of my plant's blooms, but not as prominent as yours. For the plants that I have flowered, I notice a general reddening rather than being concentrated on the pedicel. I have also noticed the stem of the growing tip of some plants develop a red tinge before blooming, but this is unreliable.

Actually, not all of the Caryophyllales produce Betalains. Two groups, the Molluginacea and Caryophyllacea (oddly enough, the namesake of the order), do not produce them and instead produce Anthocyanins in their place. It is thought these two families lost the ability to produce Betalains after evolving from a common ancestor.

Cheers,

Chooka

Edited February 16, 2011 by Chooka