Hawaii. Macrothelypteris torresiana is native from the Old World Tropics to Madagascar and Polynesia, and has become widely naturalized in the Americas including the southern United States. In the Hawaiian Islands,
Kaua`i, O`ahu, Maui, Hawai`i.
Found in disturbed and open areas in mesic forests.
Plants medium-sized to somewhat large, terrestrial. Rhizomes decumbent, short-creeping.
Fronds 55-150(-180) cm long, erect. Stipes straw-colored, scales at bases narrow, dark brown, soon deciduous, distally stipes glabrous, smooth. Blades 3-pinnate-pinnatifid to 3-pinnate-pinnatisect, deltate to linear-deltate, about as long as stipes; rachises glabrous, 2-grooved adaxially, grooves separated by a rounded ridge covered with fine, white, sharp-tipped hairs. Pinnae lanceolate, alternate, to 32 cm long. Pinnules arising obliquely from midrib, to 8 cm long, mostly cut to narrow wings along pinna rachises, abaxial surfaces with many scattered, white, needlelike hairs; costae with similar hairs on both surfaces. Ultimate segments crenulate to deeply lobed, lobes pointing obliquely toward tips.
Sori medial, round, bearing hairs. Indusia small, inconspicuous, soon deciduous, or hidden by mature sporangia.