vulpic

from The Century Dictionary.

• Noting an acid, a yellow compound, CH₃O.COC (C₆H₅): C.C(OH): C(C₆H₅)CO.O, contained in Letharia vulpina and in various other lichens. It crystallizes in thin, mono-clinic plates, or in thick, transparent prisms, and melts at 148° C. Also called methyl pulvate.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Chem.) Pertaining to, derived from, or designating, an acid obtained from a lichen (Cetraria vulpina) as a yellow or red crystalline substance which on decomposition yields pulvinic acid.