The proper (often shield-shaped) covering of the sorus or fruit-dot in Ferns.
Indusium minute, concealed beneath the sorus, divided into a few beaded hairs.
The indusium arises from a vein to which the sorus is attached.
The sorus, as the group of sporangia is called, is surrounded by an enclosure from the leaf margin.
Indusium hood-shaped, fixed centrally behind the sorus and arching over it, soon withering, often illusive.
Commonly the spore-cases occupy only detached spots or lines, each of which is called a sorus, or in English merely a Fruit-dot.
The sorus is circular and is covered with an indusium which is notched or kidney-shaped.
Indusium star-shaped, of a few irregular segments fixed beneath the sorus, often obscure.
In this case the sorus is always near to the margin of the leaf, and the indusium or covering is cup-shaped.