Adiantum pedatum L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Rhizome short-creeping, 3–5 mm thick, its scales light brown, 3–6 × 1–2 mm; lvs few or solitary, with an erect, purple or purplish-black petiole 1–6 dm, the blade shorter and set nearly at right angles to the petiole, mostly 1–4 dm long and about as wide, or wider, reniform-orbicular when well developed, subequally forked at the top of the petiole into 2 recurved- spreading rachises that bear 2–several progressively shorter pinnae along the outside of the curve; larger pinnae with mostly 15–35 alternate, short-stalked, widely spreading pinnules on each side of the costa; pinnules 12–22 × 5–9 mm, obliquely oblong, the midrib near the lower margin, which is entire and straight or concave, the upper (distal) margin more convex, lobulate, and bearing the oblong indusial flaps; 2n=58, 116. Moist Woods and streamsides in circumneutral soil, and on serpentine slopes at scattered stations from Nf. to Vt.; Nf. to Alas. and adj. Asia, s. to Ga., La., Okla., and Calif. Most e. Amer. plants belong to the nomenclaturally typical phase of the sp.; serpentine plants from both e. and w. N. Amer. tend to have fewer and smaller pinnae and have been segregated as subsp. calderi Cody.
northern maidenhair fern