Stems long-creeping, slender; scales brown, many, broadly lanceolate. Leaves dimorphic, deciduous, few, well separated; sterile leaves 40-58 cm, fertile leaves 49-70 cm. Petiole reddish brown proximally, straw-colored distally; base not swollen, with sparsely set brown scales. Blade bright green, generally lanceolate, scaly-glandular upon emergence but soon glabrate; sterile leaves pinnatifid, 13-26 cm; fertile leaves pinnate, sharply contracted, 20-27 cm. Pinnae not articulate to rachis, arranged in 7-12 alternate pairs; sterile pinnae lanceolate, 3-11 × 1-2.5 cm; fertile pinnae contracted, linear, 3-11 × 0.2-0.5 cm. Veins anastomosing into 2 or more rows of areoles between costae and margin, free only at blade margin. Sori linear-oblong, deeply sunken into blades, nearly occupying full breadth of blade. Indusia ± membranous, lacking thickened cells, tucked under sporangia, not recurving but mostly disintegrating with age. 2 n = 70.
"Rhizome 2–3.5 mm thick; lvs dimorphic, 3–8 dm, the sterile ones with stramineous petiole and deltoid-ovate blade 10–17 cm wide, deeply pinnatifid or nearly pinnate at the base, the segments 7–10 pairs, 1–2 cm wide, finely serrulate, net-veined with several series of areoles, but the veins free at the margin; fertile lvs surpassing the sterile, with shining, purple-black petiole, the segments narrowly linear, with a single series of areoles along the costa; indusia linear, 4–8 mm, opening tardily and not reflexed in age; 2n=70. Swamps and wet woods in acid soil; N.S. to n. Fla., w. to Mich., Mo., and e. Tex., commonest on the coastal plain. (Lorinseria a.)"