The habitats of the 10 species of Woodferns that grow in Michigan are wet meadows, marshes, bog margins [D. cristata, D. spinulosa, D. intermedia (on hummocks)] swamps, swamp margins, wet thickets, low wet woods [D. cristata, D. spinulosa, D. filix-mas (limesinks) D. intermedia, D. celsa, D. clintoniana, D. marginalis, D. goldiana]; high, moist beech-sugar maple-basswood forests (D. intermedia, D. marginalis, D. goldiana, D. expansa, D. spinulosa, D. filix-mas); shaded upland ravine slopes (D. marginalis, D. intermedia, D. expansa); dry upland pine or pine-poplar-oak forests (D. marginalis, D. spinulosa, D. intermedia); and rock cliffs (D. fragrans, D. filix-mas, D. marginalis, D. intermedia). Usually the frequency of interspecific hybridization among the Woodferns is directly proportional to the frequencies in which their parents are associated, but there are exceptions. Perhaps because of a genetic, mechanical, and/or ecological barrier, certain hybrids are rarer than would be expected from the frequencies with which their parents occur together.