From a number of lichens. Belongs to the group of lichen acids. Isoln: Paterno, Ogliarori, Gazz. Chim. Ital. 1877, 189; Hesse, Ber. 30, 357, 1983 (1897); St. Pfau, Helv. Chim. Acta 9, 650 (1926). Synthesis: Neelakantan et al., Tetrahedron Lett. 1962, 287. TLC analysis: R. Klee, L. Steubing, J. Chromatogr. 129, 478 (1976); J. L. Ramaut et al., ibid. 155, 450 (1978).