Paraphyses

Approximately one-third of fern species have paraphyses of one type or another. These are sterile hairs or scales intermixed with the sporangia, and they are, like indusia, believed to perform a protective function. Paraphyses usually are hairs or modifications of hairs that arise among the sporangia or on the sporangial stalk or capsule. In various genera of ferns, the paraphyses have proved to be helpful sources of taxonomic data.