from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. of or relating to usnic acid
from the GNU version of the Collaborative International Dictionary of English
- adj. Pertaining to, or designating, a complex acid obtained, as a yellow crystalline substance, from certain genera of lichens (Usnea, Parmelia, etc.).
from The Century Dictionary and Cyclopedia
- Pertaining to, or derived from, Usnea or other licliens.
Sorry, no etymologies found.
The accumulation of the protective pigment parietin in Xanthoria parietina is induced specifically by UV-B radiation , while in Cladonia uncialis and Cladina rangiferina only UV-A radiation had a stimulating effect on the accumulation of usnic acid and atranorin, respectively.
Usnic acid levels in old lichen specimens from herbariums show lower levels of usnic acid than recent specimens from the same place, indicating that UV-B levels were lower in recent history.
Certain species of lichens (e.g. Usnea aurantiaco-atra) produce higher levels of usnic acid when levels of UV-B are higher.
As most have figured out, there's no reason to believe usnic acid is the source of elk fatality found in the lichen.
One final one, let me mention as well, usnic acid.