Roccella

from WordNet (r) 3.0 (2006)

roccella
    n 1: a source of the dye archil and of litmus [syn: {roccella},
         {Roccella tinctoria}]

from The Collaborative International Dictionary of English v.0.48

Orcin \Or"cin\, n. [Etymology uncertain: cf. F. orcine.] (Chem.)
   A colorless crystalline substance, {C6H3.CH3.(OH)2}, which is
   obtained from certain lichens ({Roccella}, {Lecanora}, etc.),
   also from extract of aloes, and artificially from certain
   derivatives of toluene. It changes readily into orcein.
   [1913 Webster]