Sorus

This Neo-Latin word is from Ancient Greek σωρός (sōrós 'stack, pile, heap').

In ferns, the sori form a yellowish or brownish mass on the edge or underside of a fertile frond.

In some species, they are protected during development by a scale or film of tissue called the indusium (pl.

Sori occur on the sporophyte generation, the sporangia within producing haploid meiospores.

The shape, arrangement, and location of the sori are often valuable clues in the identification of fern taxa.