Synonyms: Polypodium sandwicensis (as sandwicense) Hook. & Am.; Dryopteris unidentata sensu auct., non (Hook. & Am.) C. Chr.; Phegopteris crinalis (Hook. & Am.) H. Mann var. tripinnata Hillebr.; Ph. sandwicensis (Hook. & Am.) H. Mann; Ph. unidentata sensu auct., non (Hook. & Am.) J. Sm.; Thelypteris sandwicensis (Hook. & Am.) Fosberg
Endemic
Named for the Sandwich Islands, an earlier name for the Hawaiian islands, + Latin suffix -ensis, indicating place or country of growth or origin.
Plants medium-sized, terrestrial. Rhizomes erect. Fronds 30-100(-125) cm long. Stipes straw-colored to light brown, scales at base narrow, twisted, linear-lanceolate, dark brown, upper stipes and rachises glabrous or with scattered hairlike scales. Blades 3-pinnate, deltate, dark green, chartaceous. Pinnae 10-16 pairs, stalked, costae and costules naked except for occasional hairlike scales. Ultimate segments short-stalked or sessile, rectangular, lobed, bases cuneate, tips obtuse, usually with 1-2 small teeth. Veins free, 1-to 2-forked. Sori submarginal, close to sinuses, on distal forks of veins. Indusia absent.
Common in scattered sites in mesic forests, 80-1,265 m, all major islands.
The name Dryopteris unidentata was erroneously applied to this species in publications and checklists, an error revealed when type specimens at Kew were examined. In this book the name D. unidentata is properly applied to the fern bearing that name. Also, the name D. sandwicensis was erroneously applied to D. mauiensis, an error also detected when the type specimens of both species were examined. (See discussions of this problem under D. mauiensis and D. unidentata.)
Dryopteris sandwicensis, a medium-sized fern of usually moderately wet forests, is characterized by sori lacking indusia and found very close to the sinuses of the ultimate segments. It has straw-colored to light brown stipes clothed at their bases with dark brown, twisted, narrow, linear scales. The upper stalks and rachises are bare and smooth (sometimes with scattered hairlike scales).