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Asian sword fern

Boston swordfern, sword fern, wild Boston fern

Stem

scales appressed, bicolored with margins transparent.

scales spreading, concolored.

Leaves

3–25 × 0.3–1.6 dm.

4–15 × 0.5–1.2 dm.

Petiole

0.4–4.4 dm, moderately to densely scaly;

scales appressed, dark brown with pale margins.

0.2–4 dm, sparsely to moderately scaly;

scales spreading, pale brown to reddish brown, concolored.

Blade

sparsely to moderately scaly, hairy abaxially, hairs pale brown, 0.1–0.3 mm.

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

Indusia

circular to horseshoe-shaped, peltate or attached at narrow sinus, 1.1–1.3 mm wide.

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

Tubers

absent.

absent.

Rachis

2.7–20 dm, points of pinna attachment 8–24 mm apart;

scales scattered to dense, brown, margins pale.

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.

Central

pinnae narrowly deltate, sometimes elliptic, 3.4–12.3 × 0.6–1.8 cm, base rounded basiscopically, slightly auriculate to truncate acroscopically (latter more common in sterile pinnae), acroscopic lobe acute to oblong, margins biserrate to irregularly serrate to serrulate, apex attenuate and occasionally slightly falcate;

costae adaxially densely hairy, hairs pale, erect, 0.1–0.5 mm.

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.

2n

= 82.

Nephrolepis multiflora

Nephrolepis exaltata

Habitat Terrestrial or epiphytic in open waste places and roadsides Terrestrial or epiphytic in forested to open habitats, most often as an epiphyte
Elevation 0 m [0 ft] 0 m [0 ft]
Distribution
from FNA
FL [Introduced in North America]
from FNA
FL; West Indies; Pacific Islands in scattered locations
[WildflowerSearch map]
[BONAP county map]
Discussion

Nephrolepis multiflora is native to the Old World tropics and is widely scattered and naturalized in the New World tropics as an escaped cultigen.

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

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.)

Source FNA vol. 2. FNA vol. 2.
Parent taxa Dryopteridaceae > Nephrolepis Dryopteridaceae > Nephrolepis
Sibling taxa
N. biserrata, N. cordifolia, N. exaltata, N. ×averyi
N. biserrata, N. cordifolia, N. multiflora, N. ×averyi
Synonyms Davallia multiflora Polypodium exaltatum
Name authority (Roxburgh) F. M. Jarrett ex C. V. Morton: Contr. U.S. Natl. Herb. 38: 309. (1974) (Linnaeus) Schott: Gen. Fil. plate 3. (1834)
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