5.
Nephrolepis exaltata
(Linnaeus) Schott, Gen. Fil. plate 3. 1834.
Sword fern, wild Boston fern
Polypodium exaltatum
Linnaeus, Syst. Nat. ed. 10, 2: 1326. 1759
Stem scales spreading, concolored. Tubers absent. Leaves 4--15 × 0.5--1.2 dm. Petiole 0.2--4 dm, sparsely to moderately scaly; scales spreading, pale brown to reddish brown, concolored. Blade glabrous, sparsely to moderately scaly abaxially near costae and adaxially. 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. 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. Indusia reniform to horseshoe-shaped, attached at narrow or broad sinus, 1--1.7 mm wide.
Terrestrial or epiphytic in forested to open habitats, most often as an epiphyte; 0 m; Fla.; West Indies; Pacific Islands in scattered locations.
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.
