Description from Flora of China
Lycopodioides boninensis (Baker) Kuntze.
Plants epilithic, evergreen, creeping, 10-30 cm, fertile stems erect. Rhizophores at intervals throughout length of creeping stem and branches, borne on ventral side in axils of branches. Main stems branched throughout, pinnately branched, stramineous, ca. 1 mm in diam. in lower part, terete, sulcate, branches few, erect fertile stems branched from middle upward; primary leafy branches 5-8 pairs, simple or once pinnately branched, secondary branches not forked or basal one or two forked, branchlets sparse, adjacent primary branches on main stem ca. 2 cm apart, leafy portion of main stem including leaves 6-8 mm wide at middle, ultimate branches 3.6-4.5 mm wide including leaves. Axillary leaves on branches symmetrical, ovate-lanceolate, 2.3-2.5 × 1.2-1.4 mm, base exauriculate, margin ciliolate. Dorsal leaves ± symmetrical, those on main stems slightly larger than those on branches; dorsal leaves on branches not approximate, ovate or ovate-lanceolate, 1.8-2.5 × 0.8-1 mm, not carinate, base subcordate or cordate, not peltate, margin ciliolate, apex acuminate or aristate. Ventral leaves asymmetrical, those on main stem larger than those on branches; ventral leaves on branches contiguous or slightly overlapping, spreading, oblong or oblong-ovate, 2.2-3.2 × 1-1.8 mm, apex acute; acroscopic base enlarged, broader, overlapping stem and branches, margin ciliolate. Strobili solitary, terminal, compact, dorsiventrally complanate, 6-8 × 2.6-3.3 mm; sporophylls dimorphic, resupinate, not white-margined; dorsal sporophylls ovate-lanceolate, not keeled, margin ciliolate, apex acute, with sporophyll-pteryx incomplete and ciliolate; ventral sporophylls ovate-lanceolate, carinate, margin ciliolate; megasporophylls in basal portion on lower side of strobilus or in basal portion on both sides; microsporangia orbicular, rather thin, cells uniform; microspores red, megaspores white-yellow.
Selaginella boninensis is similar to S. heterostachys and S. effusa but differs in the plants always creeping.
Slopes in tropical forests, trailsides, roadsides; 100-500 m. S Taiwan [Japan (Bonin Islands)].