Endemic

Latin rubiginosus, rusty, in reference to the color of the scales on the stipes and rachises of dried specimens.

Rhizomes decumbent to erect. Fronds 30-90 cm long. Stipes covered with abundant shiny, rigid, white-transparent, hairlike scales (white and lustrous on living specimens, rusty brown on dried specimens), occasionally some scales on living specimens tan. Blades 3-to 4-pinnate, ovate-deltate; rachises deeply grooved adaxially, the grooves continuous with those of costae and midribs, appearing hairy with hairlike scales similar to those of stipes. Pinnae alternate, linear-deltate, short-stalked, costae and pinnule midribs appearing hairy with hairlike scales similar to those of stipes. Ultimate segments oblong with crenulate margins. Sari round. Indusia small, reniform. Locally common in mesic to wet forests, 885-2,180 m, all major islands.

Nothoperanema rubiginosa stands out prominently in the forest because of its stipes and rachises abundantly covered with silvery white to translucent, hairlike scales. It is the only Hawaiian fern with such an abundantly lustrous, hairy appearance. The hairlike scales change remarkably when dried, becoming brown to rust-colored.

Reference: Smith & Palmer (1995).