The wooly hairs of the alpine edelweiss protect the plant's cells from ultraviolet radiation by acting as photonic structures that interact with and absorb the UV radiation.

“Want to protect yourself from sun damage? Slathering yourself in
edelweiss could help. Edelweiss is a mountain flower and so is exposed
to a large amount of ultraviolet light. Just how it protects itself from
tissue damage at such high altitudes has been a mystery, says Jean Pol
Vigneron at the University of Notre-Dame de la Paix in Namur, Belgium.
Vigneron and his colleagues measured the spectrum of light reflected
from the plants and found that while most wavelengths are reflected, UV
is not. ‘It’s astonishing, but the plant completely absorbs the UV,’
says Vigneron. The team then examined the tiny, white hairs that cover
edelweiss leaves under a scanning electron microscope. They found that
the hairs are made up of parallel fibres 0.18 micrometres across, which
is close to the wavelength of UV light. This means they can interact
with UV light, steering it along the length of the leaves, says
Vigneron. In this way, the UV light is absorbed over a large number of
hairs instead of penetrating to the plant’s body. The trick should be exploited to create a
‘natural’ sunscreen for people, says Vigneron. ‘We currently use
sunscreens made of titanium dioxide particles, but these can be absorbed
through the skin and can be harmful,’ he says.” (New Scientist 2007)

Last Updated September 14, 2016