Leaves 2-pinnate; petioles ± length of blades, winged, with light brown hairs, glabrate at maturity. Sterile leaves broadly ovate, ca. 0.75--1 m; pinnae lanceolate, lacking tuft of hairs at base; pinnules short-stalked, base oblique to somewhat truncate, margins subentire to remotely dentate, apex acute to rounded. Fertile leaves with greatly reduced sporangia-bearing pinnae at apex. Sporangia greenish, turning red, then rusty brown. 2 n =44. Sporulation early spring--midsummer; 0--2300 m; St. Pierre and Miquelon; N.B., Nfld., N.S., Ont., P.E.I., Que.; Ala., Ark., Conn., Del., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis. The chloroplasts within the spores give the young sporangia their green color. As the spores mature and are shed, the sporangia change color to a distinctive rusty brown.