What is "lichenic acid"

Fumaric \Fu*mar"ic\, a. (Chem.) Pertaining to, or derived from, fumitory ( Fumaria officinalis).

Fumaric acid (Chem.), a widely occurring organic acid, extracted from fumitory as a white crystallline substance, C2H2(CO2H)2, and produced artificially in many ways, as by the distillation of malic acid; boletic acid. It is found also in the lichen, Iceland moss, and hence was also called lichenic acid.

n. 1 (context chemistry English) An organic acid, C₁₄H₂₄O₃, obtained from Iceland moss. 2 (context chemistry obsolete English) fumaric acid