Salvinia is a heterosporoues water fern. The microsporangia and megasporangia are borne within special reproductive structure called sporocarps. These are borne terminally in clusters on the segment of submerged leaves. Sporocarps are strictly monosporangiate, i.e., they bear either only microsporangia or megasporangia. Viroids are single stranded RNA molecules. The female reproductive organ is archegonia in gymnosperms.