Well, I thought it would be about time to go one step beyond still photography and show it as video now!
[ click links to see the videos in 1280x720 resolution and 16:9 format]
Bidens ferulifolia VIS
Bidens ferulifolia VIS HD video
Bidens ferulifolia Bee Vision using XBV2 filter
Bidens ferulifolia Bee Vision HD video
I have not seen videos of flowers in ultraviolet (UV) before, but the second video clearly shows that prominent UV pattern Bidens exhibits. The spectrometric reflection measurement of such a flower clearly shows the UV reflection of the petal tip (white line), whereas the rest of the petal is just bright yellow (turqouise line).
Using the XBV2 "Bee Vision" filter and an UV sensitive video camera, it is now possible using a UV transmitting lens (my X35 lens which allows up to 320nm in that case) and lightsource (ambient light plus my Nichia 365nm UV LED) to make that pattern visible - also in a video. So what you see in the 2nd video actually is a mapping of UV+B+G+R channels into our human visible B+G+R channels. [Since bees don't see red, the R channel could be (easily) suppressed in that 2nd video, but that hasn't been done here yet]
The XBV and XBV2 filters are my special development, so if that interest you, just ask me about it.
Stay tuned, more will follow on that fascinating subject...
More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos