amphithecium

noun, plural am·phi·the·ci·a [am-fuh–thee-shee-uh] /ˌæm fəˈθi ʃi ə/.

1. Botany. the layer or one of the layers of cells in the capsule of a moss surrounding the spores.
2. Mycology. (in certain lichens) a layer of cells that surrounds the fungal apothecium.

noun plural -cia (-sɪə)

1. the outer layer of cells of the sporophyte of mosses and liverworts that develops into the outer parts of the spore-bearing capsule