Cystopteris sandwicensis sensu C. Chr., non Brack.; Filix douglasii (Hook.) W. J. Rob.

Endemic

Name honors David Douglas (1798-1834 ), Scottish botanist who collected plants in North America, China, and Hawai'i and introduced many American plants to Europe, including the Douglas fir that bears his name.

Stipes straw-colored, thin, 0.5-1.5 mm diam. at base, glabrous, 1/3-1/2 frond length. Blades ovate-lanceolate, dark green, tips obtuse, 10-30 x 4-10 cm; rachises slightly winged, especially toward tips. Pinnae linear-triangular, tips blunt, stalks 1-2 mm long, slightly winged, margins often crenulate, den-tate. Pinnules close, erect to slightly oblique, broad, 2-3 x longer than wide, margins conspicuously and coarsely dentate. Sori medial. Indusia small, hoodlike, attached at base.

Rare in mesic forests and cave mouths, 1,500-3,000+ m, on East Maui and Hawai 'i. It grows on wet, protected ledges and within lava tube entrances in the higher-elevation subalpine and alpine zones.

Cystopteris douglasii may be separated from Cystopteris sandwicensis by its ovate-lanceolate, obtuse-tipped fronds; blunt-tipped pinnae; short pinna stalks; wider pinnules that are closer to each other; and medial sori.