The inner layer of the peridium, the protective covering of fungal fruiting bodies.
From 'endo-' (within) + 'peridium' (Latin/Greek hybrid term for the outer membrane). This singular noun form names the specific anatomical layer in fungi.
When you step on a puffball and get that dramatic cloud of spores, you're breaking through the outer peridium to expose the endoperidium—fungi evolved this elegant two-layer design to control exactly when and how spores are released to the wind.
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