Aspidium hawaiiense Hillebr.; Dryopteris filiix-mas (L.) Schott subsp. hawaiiensis C. Chr.
Hawai 'i, + Latin suffix -ens is, indicating place or country of growth or origin.
Plants medium-sized, terrestrial. Rhizomes decumbent. Fronds 45-75(-100) cm long. Stipes 1/33-1/22 frond length, 2-5 mm diam. at base; stipe base scales brown, dark brown, to light reddish brown, Iinear-lanceolate, scales dense at bases, to 2 cm long, mostly shorter, less plentiful and shorter distally. Blades 2-to 3-pinnate, linear-triangular, 25-59 cm long; rachises also scaly. Pinnae 12-18 pairs, 8-20 cm long, close to overlapping, deltate-lanceolate, costae grooved, costae and veins scaly on abaxial surfaces. Pinnules short-stalked proximally, adnate distally, lobed to again pinnate, mid-ribs grooved, abaxial surfaces with scales and hairlike scales tapering to uniseriate, multicellular, hairlike tips, and appressed glands, especially along veins. Ultimate segments linear-triangular, wider at bases, lobes oblique, tips with 1-3 acuminate teeth. Veins free, simple or forked. Sori, when present, found on nearly every pinnule and to tips of blades, medial, 4-6 per segment, usually on most distal vein forks, larger than 1 mm diam. Indusia present, usually prominent, round to reniform.
Infrequent, but sometimes abundant in spots in mesic to wet forests, 600-2,000 m, on all major islands except Lana 'i. This species and Dryopteris glabra and its varieties are the only indusiate 2-to 5-pinnate ferns found in Hawai 'i.
Dryopteris hawaiiensis, a distinctive, scaly, indusiate fern, is most often con-fused with D. glabra, but has stipes, ra-chises, and costae clothed with dark, long, lanceolate scales and prominent medial sori. Dryopteris glabra has few scales, and prominent medial sori. Dryopteris glabra has few scales, and its sori are marginal to submarginal.