isidium

noun isid·i·um \ īˈsidēəm \

Definition of isidium

plural isidia \-ēə\

: an outgrowth from the surface of the thallus in certain lichens that resembles a soredium

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Origin and Etymology of isidium

New Latin, from Isidium, supposed genus of lichens, irregular from Isis genus of gorgonians + Greek eidos form; from the resemblance of lichens that have isidia to gorgonians