UV times
In botany, a UV mark is understood to mean areas in flowers which, in addition to the colors of the visible light spectrum, also reflect or absorb UV light and thus contrast. UV patterns can be structural or caused by pigments. These areas can be limited to individual flower organs or parts thereof, but can also form a pattern at the inflorescence level . The patterns of the UV marks are not coupled with the patterns of visible light. So find z. B. clear UV marks in the center of the flowers of crepis and dandelions , which are not noticeable in the wavelength range visible to humans.
UV marks are particularly common in bee-pollinated species , as bees can also perceive parts of the ultraviolet spectrum. Some bird-pollinated flowers also show UV patterns; Some birds, as tetrachromats , are able to perceive patterns in the near UV range.
Markings that absorb UV light, so-called juice marks, can appear in the UV markings . In unusual or difficult to exploit flower shapes, they lead bumblebees and bees to the source of food.
To examine whether there are UV marks in a flower, it can be colored black with FeCl 3 dissolved in petroleum ether .
A more direct proof is possible with UV photography or UV videography. Various black and white films and CCD chips are sensitive and therefore suitable for imaging processes. A UV-permeable lens, an IR-blocker and a UV-pass-filter make the imaging of UV-reflection and -absorption possible.
In addition, commercially available spectrographs can be used to generate reflection spectra that enable the reflected and absorbed wave ranges to be evaluated.