<em>Each sporangium is a capsule that contains spores. They are usually aggregated into clusters called sori. The position and arrangement of the sporangia are very important for the identification of ferns. Fronds that have sporangia on their underside are fertile, and those that don't are sterile Ferns don't have seeds; they have spores. The spores are usually on the underside of the fronds. To reproduce, the fern releases the spores into the air. The spores don't grow into new ferns. </em>
