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Boston swordfern, sword fern, wild Boston fern

giant sword fern


scales spreading, concolored.

scales loosely appressed to spreading, concolored or bicolored with pale margins.


4–15 × 0.5–1.2 dm.

2–22 × 0.3–3.5 dm.


0.2–4 dm, sparsely to moderately scaly;

scales spreading, pale brown to reddish brown, concolored.

0.2–5.4 dm, sparsely to moderately scaly;

scales spreading, reddish to light brown throughout (rarely with pale margins).


glabrous, sparsely to moderately scaly abaxially near costae and adaxially.

sparsely to densely scaly, glabrous or pubescent, hairs mostly on veins and abaxial, pale to light brown, 0.2–0.7 mm.


reniform to horseshoe-shaped, attached at narrow or broad sinus, 1–1.7 mm wide.

circular to horseshoe-shaped, peltate or attached at narrow sinus, 0.8–1.1 mm wide.





2.4–16.3 dm, points of pinna attachment 7.3–21 mm apart;

scales moderately spaced, pale to dark brown, essentially concolored or margin indistinctly paler;

hairs absent.

1.8–17 dm, points of pinna attachment 7.5–35 mm apart;

scales moderately spaced, pale brown throughout.


pinnae deltate-oblong, slightly to distinctly falcate, 2.3–7.4 × 0.6–1.8 cm, base truncate to truncate-auriculate or auriculate, occasionally overlapping rachis, acroscopic lobe deltate to acute, margins serrulate, apex acute to deltate;

costae adaxially glabrous.

pinnae narrowly deltate to narrowly elliptic-lanceolate, 2.5–23 × 0.5–2 cm, base cuneate, truncate to auriculate-cordate acroscopically, rounded basiscopically, acroscopic lobe small and oblong or absent, margins biserrate to serrulate, apex attenuate;

costae adaxially glabrous or densely hairy, hairs erect, pale, 0.3 mm.


= 82.

Nephrolepis exaltata

Nephrolepis biserrata

Habitat Terrestrial or epiphytic in forested to open habitats, most often as an epiphyte Terrestrial or less commonly epiphytic in forested, relatively wet habitats, e.g., swamps, but occasionally thickets, roadsides, or clearings
Elevation 0 m (0 ft) 0 m (0 ft)
from FNA
FL; West Indies; Pacific Islands in scattered locations
[WildflowerSearch map]
[BONAP county map]
from FNA
FL; Mexico; Central America; South America; West Indies; Africa; se Asia

Nephrolepis exaltata is occasionally found farther north in the flora, but only as an escape from cultivation. Nephrolepis exaltata is usually confused with N. cordifolia when sterile; the latter species can be distinguished by its distinctly bicolored, adaxial rachis scales. These bicolored scales will distinguish N. cordifolia from all of the other species, even in the absence of other key features.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Some forms of Nephrolepis biserrata closely resemble N. multiflora in pinna shape and indument but lack the distinctively transparent-margined (i.e., bicolored) and persistent petiole scales of the latter species. Nephrolepis multiflora also has more appressed and darker-colored stem scales.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 2. FNA vol. 2.
Parent taxa Dryopteridaceae > Nephrolepis Dryopteridaceae > Nephrolepis
Sibling taxa
N. biserrata, N. cordifolia, N. multiflora, N. ×averyi
N. cordifolia, N. exaltata, N. multiflora, N. ×averyi
Synonyms Polypodium exaltatum Aspidium biserratum
Name authority (Linnaeus) Schott: Gen. Fil. plate 3. (1834) (Swartz) Schott: Gen. Fil. plate 3. (1834)
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