Wednesday, September 7, 2016

How to stand out in the crowd - Gazania rigens shows its ecologic advantage vs Rudbeckia fulgida and Rudbeckia hirta using intense UV reflection IV

Today about how even some UV reflecting flowers (Gazania rigens) have achieved a competitive edge over other UV reflecting flowers (Rudbeckia fulgida) by making use of a specific very intense UV reflection around 370nm. This will be shown in human vision, in reflected ultraviolet photography and also by using reflection spectrometry. I was using my "work horse" UV filter, the Baader-U filter for reflected UV and a calibrated UV-VIS USB2000 spectrometer with stabilized Xenon lightsource.

[click on image to see a larger one]

Rudbeckia fulgida + R. hirta vs white Gazania rigens, visible image:  

Rudbeckia fulgida + R. hirta vs white Gazania rigens, reflected UV image:  

Reflection spectrometry result of Rudbeckia fulgida vs white Gazania rigens (UV bright petal tip):  

In visible light, all these flowers are rather bright yellow / orange (Rudbeckia) and white (Gazania) to our human eye. But the white Gazania rigens compared to the Rudbeckia fulgida flower shows an even more prominent and bright bullseye pattern in reflected UV (only visible to bees and butterflies), as its outer petals are very UV bright (around 370nm) with a UV reflection above 60%, compared to the other UV reflecting flower with only about 10% UV reflection of its petal tips, which makes this Gazania clearly even more visible in UV, hence creating an impressive competitive edge in terms of chances for getting pollinated even against those other flowers with UV bullseye pattern - and all this gets nicely visible.

I have written HERE about it before.

Stay tuned, more will follow on that fascinating subject...