Athyrium kaalaanum Copel.; Asplenium marginate Hillebr. var. depauperata Hillebr.; Diplazium kaalaanum (Copel.) C. Chr.
Endemic
Named for the Ka'ala area of Kaua 'i, where the species was discovered.
Plants small, terrestrial. Rhizomes decumbent to erect. Fronds 15-30 cm long, sometimes proliferous near tips of rachises. Stipes straw-colored, sparsely scaly. Blades oblong-lanceolate. Pinnae 9-11 pairs, oblique, short-stalked, linear to linear-lanceolate, basal pinnae smaller. Ultimate segments oblique. Veins arranged obliquely.
Rare and restricted on rocky banks of streams and in wet forests on Kaua'i (Ka'ala area, east of Waimea Canyon), Maui (Kipa-hulu), and Hawai'i (near Hilo and Laupahoehoe). The elevational distribution is unknown.
Deparia kaalaana, a probably extinct small relative of D. marginalis, may be distinguished from the latter by its smaller, short-stalked, and obliquely arranged pinnae, ultimate segments, and veins.