According to Michigan State University there are a number of ferns that are present in Michigan floodplain forests. They include the ostrich fern (Matteuccia struthiopteris, Dryopteridaceae), sensitive fern (Onoclea sensibilis, Dryopteridaceae), royal fern (Osmunda regalis, Osmundaceae), New York fern (Thelypteris noveboracensis, Thelypteridaceae), and the rare log fern (Dryopteris celsa, Dryopteridaceae). While I’m familiar with most of these (especially the common and rather large ostrich fern) I recently came across a fern MSU didn’t mention: a bladder fern (Cystopteris sp., Dryopteridaceae).
These ferns were relatively small, with fronds less than a foot in length. They were growing just above the River Raisin on a steep north-facing bank.
Unlike seed-producing plants like angiosperms and gymnosperms, ferns are more ancient and spread via spores. The undersides of some leaves have structures called sori that are collections of spore-producing sporangia. In bladder ferns, each sorus is enclosed in an inflated membrane called an indusium. This layer ultimately ruptures and releases the spores.