indusia

noun, plural in·du·si·a [in-doo-zee-uh, -zhee-uh, –dyoo-] /ɪnˈdu zi ə, -ʒi ə, -ˈdyu-/.

1. Botany, Mycology. any of several structures having a netlike or skirtlike shape, as the membranous overgrowth covering the sori in ferns.
2. Anatomy, Zoology.
   1. an enveloping layer or membrane.
   2. a thin layer of gray matter on the corpus callosum.

noun plural -sia (-zɪə)

1. a membranous outgrowth on the undersurface of fern leaves that covers and protects the developing sporangia
2. an enveloping membrane, such as the amnion

Plural indusia

1. A thin membrane covering the sorus of a fern. The indusium often shrivels away when spores are ready to be dispersed. Also called fruitcover
2. A cuplike structure fringed with hairs and located at the top of the style in flowers of the family Goodeniaceae (which includes the garden flowers lobelia and scaevola). Pollen is deposited into the indusium by the anthers of the same flower and, as the style grows, carried up for dispersal by pollinating insects.