Curled-up sadleria fern This is an 'ama'uma'u fern, or sadleria fern (sadleria cyatheoides), curled up and not yet deployed as a full-fleged fern. As seen along the Kaupo Trail in Haleakala NP.
This image is from the presentation "A Hawaiian Kaleidoscope - Maui: Haleakala Climb and Downhill Cycle Descent, Snorkeling".