Synonym(s): Lycopodium serratum Thunb. ex Murray; Urostachys serratus (Thunb. ex Murray) Herter

Indigenous

Latin serratus, serrate, toothed like a saw; allu~ing to the serrate leaf margins of this species.

Plants terrestrial, occasionally forming large clonal 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 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. Gemmae reniform, 4-4.5 x 3.5-4 mm.

Found in wet forests, 520-1 220 m all major islands except Maui, but collected only once each on Moloka'i and Lana'i. Its ange extends to China, India, Southeast Asia, Korea, the Philippines, Indonesia, and Japan.

A form from Kaua'i with smooth margins, usually smaller leaves, and conspicuous "petioles" needs further investigation. Huperzia serrata may be recognized by its obovate, often paddle-shaped leaves with constricted, petiolelike bases. The leaf margins have larger and more irregular teeth than those of other Hawaiian Huperzin species.