Moss mats at the base of trees in very wet rain forests (occasionally in transition to mesic forests on Kaua'i).
Elevation
600-1950 m
Habit
Plants extremely variable, usually epigeous, growing on and in moss mats at base of trees; rhizomes long-creeping, slender, 1-3.5 mm diameter including scales, rhizomes not touching ground.
Leaves
Fronds (8-)12-25(-50) cm long; stipe 1-2 cm apart, 0.8-1.4 mm diameter, narrowly winged bilaterally, pale brown; blade 2-pinnate-pinnatifid to 3-pinnate (occasionally 2-pinnate), ovate-lanceolate to deltate, with many small, red, or reddish brown glands; pinnae spreading, close (often overlapping) to well separated, 1-pinnate to fully 2-pinnate over entire pinna, basal pinnae reduced or not; pinnules spatulate or oblong, broad or narrow, with up to 10 pairs of ultimate segments; acroscopic basal pinnule often very enlarged and again pinnatifid to 1-pinnate; basal pinnules more divided than more distal ones: tips blunt or acute; ultimate segments linear, oblanceolate to acutely spatulate; veins with tips projecting beyond sori.
Sori
Sori abaxial, subapical, seldom as wide as ultimate segments.
Notes
Latin tres, three, + pinna, winged, feathered, plus -fid, divided into many parts, in reference to its 3-pinnate quality.
