Asplenium amoenum C. Presi; A. resectum Sm.; Hymenasplenium unilatera/e (Lam.)

Common names: pamoho

Hayata Indigenous

Latin unus, one, + lateralis, at the side, lateral to, alluding to the apparently one-sided dimidiate pinnae.

Plants small to medium-sized, terrestrial or epipetric. Rhizomes long-creeping, thin, up to 3.5 mm diam. Fronds erect, well separated, spaced up to 4 cm apart, 15-35 x 2-4.5 cm, not proliferous. Stipes and rachises thin, round to shallowly grooved, dark brown to black, shiny, glabrous. Blades 1-pinnate, deltate-lanceolate, tips tapering gradually and evenly. Pinnae 12-25 pairs, short-stalked, alternate, rectangular with somewhat tapering tips, strongly dimidiate with lower margins of pinnae nearly straight to mod· erately concave, usually less than 2.5 x 0.8 cm, costae close to lower margins, distal margins finely dentate; lower-pinnae not or only slightly reduced. Veins conspicuous, 1· to 2-forked. Sori to 3 mm long. Indusia thin.

Locally common fern of wet, mossy forests, often near streams, 200-1,830 m, all major islands. Also widely distributed from China to Africa, Malaysia, southern Japan, Taiwan, China, and Polynesia.

Some authors place both this species and Asplenium excisum in the genus Hymenas-plenium, largely because of their distinctive, narrow, long-creeping rhizomes and well-separated fronds.

Asplenium unilaterale, a 1-pinnate fern, resembles and is sometimes confused with A. excisum, with which it shares the same slender, long-creeping rhizome type; however, A. unilaterale may be identified by its smaller fronds, smaller pinnae size, less concave lower pinnae margins, upper pinna margins with finer teeth, and frond tips that usually taper gradually and evenly.