Sorus of Cyrtomium

         By Justin Walley

Cyrtomium is a member of  the Leptosporangiate ferns called Filicales which are homosporous.  One of the characteristics that distinguishes Leptosporangiate ferns from Eusporangiate ferns is the presence of annulus and lip cells in the sporangium.  Spores are released when the annulus cells shrink and break open the sporangium in the lip cell region.  The indusium is a specialized portion of recpticle that protects the sori.