Polypodium triseriale

Stems not whitish pruinose, slender to stout, 5--15 mm diam., taste unknown; scales brown, ovate-acuminate, symmetric, somewhat to strongly clathrate, margins somewhat lighter, entire. Leaves to 90 cm. Petiole slender to stout, to 7 mm diam. Blade broadly ovate, 1-pinnate at base, widest at or near base, to 60 cm wide, papery to almost leathery; rachis glabrous abaxially and adaxially. Segments (pinnae) linear to oblong, apex acuminate; proximal segments stalked to nearly sessile, distal ones slightly narrowed but broadly adnate at base, less than 35 mm wide; margins entire or slightly wavy; apex acute; midrib glabrous adaxially. Venation anastomosing with a regular series of 2--5 rows of areoles on both sides of costae. Sori in 1--3 parallel rows on both sides of costa, 0.5--3 mm diam., circular when immature. Sporangiasters absent. Spores less than 58 µm, verrucose, with surface projections less than 3 µm. 2 n = 148.

Epiphytic; 0 m; Fla.; s Mexico; West Indies; Central America; South America to s Brazil, Bolivia.

Commonly found in montane tropical rainforests, the epiphytic Polypodium triseriale is quite distinct from and probably only distantly related to other North American members of Polypodium . It seems likely that spores are occasionally blown into southern Florida, probably from the West Indies, and plants develop as naturalized populations.