Purple Willow leafs UV, Heesch, Netherlands
A while ago, I made a nightly stroll through our small garden to pre-select UV subjects. I used a 320nm light, sometimes called "pure UV". This in contrast to popular UV flashlights that above all are powerful yet not pure in their wavelength.
Given a suitable light, we expose the subject to it exclusively, no other light should interfere. If its a UV "sensitive" subject it will "reflect" back color in the visible spectrum. Succesful subjects in the same garden:
This particular subject caught my eye during the UV round. This cultivated Salix purpurea lit up like a faint christmas tree. In particular, it seems the jagged edges of each leaf (and there's hundreds on this tree) create little light sparks whilst every other part of this plant/tree does nothing, and remains dark. I'm not convinced it has any biological function, but it does look cool.
Transfering this effect to a photo is difficult, and I find the result underwhelming compared to the real experience. So you kind of have to image this photo times 500 for what it looks like in the real world.
Making of: I took a few leafs and taped them to end of a lens hood, effectively creating a small dark chamber. Next, I aimed the UV light inside and exposed for 2 minutes using my 1:1 macro lens.