From Flora of Indiana (1940) by Charles C. Deam
Frequent in the lake area, becoming infrequent to local south of it. In the lake area it is usually common in tamarack bogs and swamps about lakes, and in the southern part of the state it grows in low, flat woods, associated with sweet gum and red maple. Throughout its range it is found only in wet soil in bogs or about ponds and marshes and rarely on shaded slopes. [Deam describes three forms. Forma auriculata] has the basal segments much elongated and deeply and sharply toothed on the lower side or rarely on both sides. The other segments are normal or nearly so. It has been found in Porter County by R. M. Tryon, Jr. [Forma frondosa] has the fertile frond partly leafy, the fertile and sterile pinnae variously intermixed. I found this unusual form in Lagrange County and Nieuwland found it in St. Joseph County. [Forma incisa] usually has acutely toothed or lobed segments. I found it in De Kalb County.