Nephrolepis exaltata |
Nephrolepis |
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Boston swordfern, sword fern, wild Boston fern |
Boston fern, swordfern |
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Habit | Plants terrestrial, epiphytic, or on rock. | |||||||||||||||||||||
Stem(s) | scales spreading, concolored. |
ascending to erect, bearing wiry stolons and sometimes underground tubers. |
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Leaves | 4–15 × 0.5–1.2 dm. |
monomorphic, evergreen. |
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Petiole | 0.2–4 dm, sparsely to moderately scaly; scales spreading, pale brown to reddish brown, concolored. |
ca. 1/10–1/2 length of blade, base not swollen; vascular bundles more than 3, arranged in an arc, ± round in cross section. |
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Blade | glabrous, sparsely to moderately scaly abaxially near costae and adaxially. |
narrowly elliptic to linear-lanceolate, 1-pinnate (to 4–5-pinnate in various cultivated forms), very gradually reduced distally to minute pinnatifid apex, often seemingly indeterminate with apex never expanded, herbaceous to papery. |
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Pinnae | articulate to rachis, sometimes deciduous, segment (pinna) margins entire, crenulate, or biserrate; proximal pinnae (usually several pairs) slightly to greatly reduced, sessile, equilateral or inequilateral with basiscopic base excised and often an acroscopic basal auricle; costae adaxially grooved, grooves not continuous from rachis to costae; indument of linear-lanceolate scales and sometimes multicellular hairs on abaxial and sometimes adaxial surfaces. |
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Veins | free, forked. |
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Indusia | reniform to horseshoe-shaped, attached at narrow or broad sinus, 1–1.7 mm wide. |
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Sori | ± round; indusia round-reniform and with deep sinus to semicircular with broad sinus or lunate without sinus and seemingly laterally attached, persistent. |
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Spores | brownish, tuberculate to rugose. |
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Tubers | absent. |
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Rachis | 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. |
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Central | 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. |
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x | = 41. |
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Nephrolepis exaltata |
Nephrolepis |
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Habitat | Terrestrial or epiphytic in forested to open habitats, most often as an epiphyte | |||||||||||||||||||||
Elevation | 0 m (0 ft) | |||||||||||||||||||||
Distribution |
FL; West Indies; Pacific Islands in scattered locations
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Widespread in tropical areas |
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Discussion | 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.) |
Nephrolepis often has veins ending in hydathodes and whitish lime-dots adaxially. Cultivars of Nephrolepis occasionally are found in the wild, where they persist for some time. Numerous forms of N. exaltata cv. `Bostoniensis' and its derivatives are widely cultivated, and the following are known from Florida: N. exaltata cv. `Bostoniensis', N. exaltata cv. `Elegantissima' complex, N. exaltata cv. `Florida Ruffles', N. exaltata cv. `M. P. Mills'. Nephrolepis falcata forma furcans (T. Moore in Nicholson) Proctor resembles N. biserrata in size, pinna shape, and sori, but it differs characteristically in having forking pinnae and rachises. It is widely cultivated and persists when escaped; it is not known to spread from spores. It is known in the literature under the following names: Aspidium biserratum Swartz var. furcans (T. Moore in Nicholson) Farwell, Nephrolepis biserrata (Swartz) Schott var. furcans (T. Moore in Nicholson) Hortus ex Bailey, and Nephrolepis davallioides var. furcans T. Moore in Nicholson. Nephrolepis hirsutula (G. Forster) C. Presl cv. `Superba' has irregularly pinnatisect, elliptic pinnae and a dense covering of reddish orange scales over most of the leaf surfaces. The report of Nephrolepis pectinata (Willdenow) Schott for Florida by E. T. Wherry (1964) was based on a misdetermination (T. Darling Jr. 1982). Species 25–30 (4 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 2. | FNA vol. 2. | ||||||||||||||||||||
Parent taxa | ||||||||||||||||||||||
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Synonyms | Polypodium exaltatum | |||||||||||||||||||||
Name authority | (Linnaeus) Schott: Gen. Fil. plate 3. (1834) | Schott: Gen. Fil. plate 3. (1834) | ||||||||||||||||||||
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