Vine ferns [Greek mikros, small, and gramme, line; the sori are elongate in the type species]

Clifton E. Nauman

Plants epiphytic or on rock. Stems long-creeping, branched, 0.5--1.5 mm diam., not whitish pruinose; scales bicolored, rhombic, glabrous, margins entire or toothed. Leaves monomorphic or dimorphic, well separated, not narrowed toward tip, to 17 cm; fertile leaves often narrower and longer than sterile leaves. Petiole articulate to stem, straw-colored to greenish, somewhat flattened. Blade simple, linear-elliptic to linear oblanceolate, glabrous, or sparsely scaly on midrib, margins entire to crenate. Veins obscure, forming a row of costal areoles and often additional areoles toward blade margins, areoles often with 1--several free included veinlets. Sori in 1 row between midrib and margin on included veinlets, discrete, round [elongate]; indument of threadlike scales or absent. Spores tuberculate to rugose. x = 37.

Species 20--30 (1 in the flora): tropical, North America, Mexico, West Indies, Central America, South America, Africa.

Lower Taxon

• Microgramma heterophylla (Linnaeus) Wherry