Lycopodium serratum Thunb. ex Murray var. den-tatum Hillebr.; Urostachys sulcinervius (Spring) Herter ex Nessel var. kauaiensis (as "kanaiensis ") Hillebr. ex Nessel

Endemic

Latin erosus, irregularly cut away and appearing eroded; alluding to the leaf margins of this species.

Plants terrestrial or epiphytic, occasionally forming large colonies. Stems decumbent, repeatedly branched, 9-30 x 0.8-1.6 cm, annual growth constrictions indistinct. Leaves reflexed to spreading, lanceolate, parallel-sided or narrowed at base, 4-8 x 1-1.5 mm, not imbricate, with slight to no reduction in leaf size between mature and juvenile portions, dark green in shade, light green in sun, yellow on decumbent portion, adaxial surfaces shiny, lustrous, margins smooth at bases, irregularly serrulate to small-toothed along distal 1/3, tips acute. Gemmae at base of nearly every leaf on large areas of stems, 3.5-4 x 3.5-4 mm.

Found in isolated patches in wet forests, 900-1,815 m, all major islands; collected only once on Moloka 'i.

Huperzia erosa may be recognized by its lanceolate, spreading leaves that are not or only minimally constricted at the bases. The leaf margins are smooth along the basal halves and have small to medium-sized, irregular teeth along the upper halves.