Secalonic acid
Secalonic acids are a group of chiral dimeric tetrahydroxanthones closely related to ergoflavin and ergochrysin A that are collectively called ergochromes and belong to a class of mycotoxins initially isolated as major ergot pigments from the fungi "Claviceps purpurea" that grows parasitically on rye grasses . 
<triplet> ergot <subj> Claviceps purpurea <obj> taxonomic type