Endemic

Greek tetra, four, + pinnatus, winged, feath-ered, in reference to the often 4-pinnate frond.

Plants huge and beautiful, very finely dis-sected, terrestrial. Rhizomes decumbent to erect. Fronds up to 3 m long. Stipes up to 1 m long, covered with long, narrow, linear-lanceolate scales, dull dark brown, dense at bases, plentiful but sparser distally. Blades 4-pinnate to 4-pinnate-pinnatisect, finely cut, oblong-lanceolate, green to dark green, coriaceous; rachises and costae straw-colored, with many scales, scales smaller and more scattered than those on stipes. Pinnae up to 25 pairs, short-stalked, 30-60 x 11-25 cm, lanceolate, greatly overlapping, costae scaly to ultimate segments. Ultimate segments very narrow, less than 2-6 x 0.8-1.5 mm wide, lobes and tips acute-tipped or toothed. Veins depressed adaxially. Sori submarginal to marginal, in sinuses on distal branches of segment veins. Indusia absent.

Scattered in understories of rain forests, 1,400-1,830 m, on the north, east, and south slopes of Haleakala on East Maui.

This spectacular fern may be the largest Dryopteris in the world.

See discussion of its relationships under D. unidentata.

Dryopteris tetrapinnata, restricted to rain forests on East Maui, may be recognized by its very large, scaly fronds with up to 25 overlapping pinna pairs, and its finely cut, 4-pinnate-pinnatifid blades. Sori are at the bases of the sinuses and have no indusia.