2. Nephrolepis ×averyi Nauman, Amer. Fern J. 69: 69. 1979.
Avery's sword fern
Stem scales loosely appressed to spreading, essentially concolored. Tubers absent. Leaves 8--30 × 0.5--1.3 dm. Petiole 1.2--5 dm, moderately to densely scaly; scales spreading, reddish to light brown throughout. Blade moderately scaly, glabrous to occasionally pubescent abaxially, glabrous adaxially, hairs pale to light brown, 0.2--0.7 mm. Rachis 5--26 dm, points of pinna attachment 9--25 mm apart; scales scattered, brown throughout. Central pinnae narrowly deltate to oblong-deltate, 3.6--9 × 0.7--2 cm, base truncate, sometimes rounded basiscopically, barely auriculate acroscopically, acroscopic lobe obtuse to acute, margins serrulate, apex narrowly acute to attenuate, falcate to slightly so; costae adaxially sparsely pubescent, hairs pale, erect, 0.1--0.5 mm. Indusia horseshoe-shaped to circular, attached at narrow sinus or peltate, 0.9--1.1 mm wide. 2 n = 164.
Terrestrial or epiphytic in forested, often moist habitats, e.g., swamps, hammocks, or relatively open, disturbed habitats; 0 m; Fla.; Mexico; West Indies.
Nephrolepis × averyi is an allotetraploid derived from hybridization between N . biserrata and N . exaltata and is known to occur only in mixed populations of both parent species. It is distinguished from N . exaltata by its sparsely hairy adaxial costae, larger size, and misshapen spores, and from N . biserrata by its falcate pinnae and narrower leaves.