Adiantum poiretii Wikstr.

Plants terrestrial or epilithic. Rhizome short-creeping, branched, to 2.5 mm in diameter, producing slender stolon-like branches, to 50 mm long, to 1.2 mm in diameter, at apex of which is produced the shorter, somewhat thicker, frond-bearing part, set with roots, crowded stipe bases and scales, scales chartaceous to crustaceous, castaneus to ferrugineous, sessile, narrowly lanceolate, cordate, entire to shallowly repand, apex terminates in a short subulate cell, to 5 mm long, to 1.2 mm wide. Fronds crowded, erect to arching, to 750 mm long, to 10 per plant; stipe firm, atrocastaneus, nitid, terete, to 360 mm long, to 2 mm in diameter, initially sparsely set with scales similar to those on rhizome, glabrous later; lamina anadromous, ovate-deltate, to 5-pinnate, to 400 mm long, to 280 mm wide, with up to 12 pinna pairs; rachis and lower order axes atrocastaneus, nitid, terete, glabrous, often somewhat flexuose; pinnae petiolate, petiole to 34 mm long, alternate, basal pinnae largest, widely spaced, more closely spaced distally, spaced or overlapping, to 4-pinnate, ovate-deltate, to 225 mm long, to 115 mm wide, with up to 9 pinnule pairs; pinnules petiolate, petiole to 22 mm long, alternate, spaced or overlapping, to 3-pinnate, ovate to elliptic, to 90 mm long, to 55 mm wide, with up to 5 segment pairs; segments petiolate, petiole to 10 mm long, alternate, ovate to elliptic, to 42 mm long, to 22 mm wide, with up to 3 pairs of ultimate segments; ultimate segments petiolate, petioles to 4 mm long, alternate filiform, articulated, thinly herbaceous, glabrous, semicircular to reniform, to 12 mm long, to 16 mm wide, lobed, lobes dentate to crenulate. Venation flabellately forked, ending in margin in sinuses between the teeth. Sori up to 7 per ultimate segment, along outer margin of lobes, lunate, to 4 mm long; receptacle with 1-3-celled hairs often producing a yellow farina, hairs to 80 mm long, similar hairs also occur on the indusial flap between veins; sporangia confined to veins entering indusial flaps, short-stalked, stalk simple, 3-seriate below capsule, capsule circular to obovate in lateral view, with 16(-19) indurated annulus cells, epistomium (4-)5-celled, hypostomium (3-)4-celled, stomium with 3 or 4 cells with conspicuously thickened walls; indusium a somewhat modified reflexed lobe margin, oblong, to 4 mm long, to 1 mm wide, margin and adaxial surface set with capitate glands and 2-to 3-celled hairs. Spores 64 per sporangium, yellow, globose, trilete, rugose, exospore (40-)43.05(-46) µm in equatorial diameter.

In montane forest; 7, 000 to 9, 000 ft. alt.