China, India, Southeast Asia, Korea, the Philippines, Indonesia, and Japan.In the Hawaiian Islands,
indigenous to
Kaua`i, O`ahu, Moloka`i, Lana`i, Hawai`i.
Terrestrial, occasionally forming large colonies; stems erect, decumbent at bases, 2- to 4-branching, 10-28 x 0.8-1.8 cm (with leaves), older portions of stems turning yellow and decaying while erect portions continue growing, becoming decumbent at bases, annual constrictions along stems conspicuous.
Leaves
Leaves spreading, reflexed, generally obovate to oblanceolate with constricted bases resembling petioles, 7-15 x 1.5-4 mm, margins coarsely and irregularly doubly serrate to erose along most of distal 1/2, contracted and entire on bases, tips abruptly acuminate, green to dark green, lustrous.
Spores
Gemmae reniform, 4-4.5 x 3.5-4 mm.
Notes
Latin serratus, serrate, toothed like a saw; alluding to the serrate leaf margins of this species.
