The Collaborative International Dictionary of English v.0.48:
Soredia \So*re"di*a\, n., pl. of Soredium. [1913 Webster]The Collaborative International Dictionary of English v.0.48:
Soredium \So*re"di*um\, n.; pl. Soredia. [NL., fr. Gr. ? a heap.] (Bot.) A patch of granular bodies on the surface of the thallus of lichens. [1913 Webster]