Flora of North America species comparison

not proliferous.

not proliferous.

short-creeping, unbranched;

scales black with lighter margins, linear-lanceolate, 1.5–3 × 0.1–0.4 mm, margins entire.

erect, rarely branched;

scales black throughout, linear-lanceolate, 1–3.5 × 0.1–0.4 mm, margins entire.

monomorphic.

monomorphic.

purplish black, lustrous, 0.5–3 cm, 1/3–1/20 length of blade;

indument of black filiform scales at base.

black or purplish black throughout, lustrous, 1–2 cm, 1/5–1/10 length of blade;

indument of black filiform scales at base.

linear, 1-pinnate throughout, 7–17.5 × 0.9–1.8 cm, thick, glabrous;

base gradually reduced;

apex gradually reduced to whiplike rooting tip.

linear to narrowly oblanceolate, 1-pinnate throughout, 5–15 × 1–2 cm, thick, glabrous;

base gradually tapered, apex acute, not rooting.

in (12–)20–40 pairs, oblong;

medial pinnae 6–9 × 3–4 mm;

base broadly cuneate or auriculate;

margins crenate-serrate;

apex obtuse.

in 12–30 pairs, oblong to quadrangular;

medial pinnae 5–10 × 2–3 mm;

base with slight or prominent acroscopic auricle and often with basiscopic auricle;

margins usually shallowly crenulate, rarely ± entire;

apex acute to obtuse.

free, obscure.

free, obscure.

3–7 pairs per pinna, on both basiscopic and acroscopic sides.

1–5 pairs per pinna, on both basiscopic and acroscopic sides.

64 per sporangium.

32 per sporangium.

purplish black throughout, lustrous, glabrous or nearly so.

black or purplish black throughout, lustrous, glabrous or with a few scattered scales.

= 2n = 180 (apogamous).