Wednesday, August 10, 2011

Mirabilis jalapa UV induced fluorescent pollen

Today about a very interesting flower, Mirabilis jalapa. This flower, also called "four-a-clock" uses a very special technique to enhance the visibility to its pollinators, in that case hawkmoths, that are active when the light gets dimmer, i.e. in the late afternoon and evening hours (hence that name). Scientists have found out, that the pollen of this flower is highly fluorescent i.e. ultraviolet light, which is proportionally more present in early morning and later afternoon hours, is "used" and downconverted to visible light (i.e. fluorescence light) according to Stokes Law. So this down converted light overlays the visible light present and so enhances the visibility to its pollinators. The yellow parts of the flower petals also exhibit green fluorescence, but to lesser extent and in green light. Now let's see how that looks like...

[click on image to see a larger one]

Left: visible image; right: UV induced visible light pollen image:

It gets strikingly visible, how intense this effect actually is!

