How to stand out in the crowd - Rudbeckia fulgida and Zinnia haageana show its ecologic advantage using intense UV reflection II

Today more about how some yellow flowers (Rudbeckia fulgida and Zinnia haageana) have achieved a competitive edge over other yellow flowers (Coreopsis verticillata in this case) by making use of a specific intense UV reflection around 365nm, matched to the insect eyes UV sensitivity. This will be shown side-by-side in human vision and also in reflected ultraviolet photography. I was using my "work horse" UV filter, the Baader-U filter for reflected UV, aside from a visible light shot. Lens was my UV-Nikkor 105mm quartz flourite lens. Light source was sunlight. All shots were done at f8.

[click on image to see a larger one]

Diptych Rudbeckia fulgida vs Coreopsis verticillata overview, visible image (left) and reflected UV image (right):  

Diptych Rudbeckia fulgida vs Coreopsis verticillata detail, visible image (left) and reflected UV image (right):  

Diptych Zinnia haageana vs Coreopsis verticillata, visible image (left) and reflected UV image (right):  

Diptych Zinnia haageana vs Coreopsis verticillata, visible image (left) and reflected UV image (right):  

In visible light, all these flowers are rather bright yellow / orange to our human eye. But this Rudbeckia fulgida and Zinnia haageana flower shows a very prominent and bright bullseye pattern in reflected UV (only visible to bees and butterflies), as their petals are very UV bright (around 350-365nm) and their center is very UV dark, compared to the rather UV non-reflecting other flowers, which makes them nearly invisible in UV, hence creating an impressive competitive edge in terms of chances for getting pollinated - and all this gets nicely visible.

I have written HERE about it before.

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