indusium

noun pl. indusia

1. Anat., Zool.
   1. any covering membrane, as the amnion
   2. a case enclosing an insect larva or pupa
2. Bot.
   1. a membranous outgrowth of the leaf epidermis in certain ferns, covering the sporangia
   2. the annulus of certain fungi

Origin: ModL < L, undergarment, tunic; assoc. with induere, to put on (see indue), but prob. < Gr endysis, dress, clothing < endyein, to go into, put on