Eusporangiate

Bailey and Pain (1971) examined the walls of a wide range of species of ferns (both leptosporangiate and eusporangiate) and divided the species into three groups depending on whether their walls contained low (0-3%), medium or high (>10%) concentrations of mannose.

In the smaller of the two groups, known as the eusporangiate type, the sporangium originates from several initial cells.

Describe structure and development of leptosporangiate and eusporangiate sporangia. Draw diagrams.